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Feature

Blast From the Past

Forty years ago, a U.S. satellite detected the telltale signs of a nuclear explosion. An analysis of the evidence today points to a clandestine nuclear test, a Carter administration cover-up, and only one country that was willing and able to carry it out: Israel.

Shortly before sunrise on Sept. 22, 1979, a U.S. surveillance satellite known as Vela 6911 recorded an unusual double flash as it orbited the earth above the South Atlantic. At Patrick Air Force Base in Florida, where it was still nighttime on Sept. 21, the staff in charge of monitoring the satellite’s transmissions saw the unmistakable pattern produced by a nuclear explosion—something U.S. satellites had detected on dozens of previous occasions in the wake of nuclear tests. The Air Force base issued an alert overnight, and President Jimmy Carter quickly called a meeting in the White House Situation Room the next day.

Nuclear proliferation was just one of the Carter administration’s headaches in late 1979. The president was dealing with a slew of foreign-policy dilemmas, including the build-up to what would become the Iran hostage crisis. Carter was also preparing for a reelection campaign in which he had hoped to showcase his foreign-policy successes, from brokering Israeli-Egyptian peace to successful arms control talks with Moscow. The possibility that Israel or South Africa, which had deep clandestine defense ties at the time, had tested a nuclear weapon threatened to tarnish that legacy. And the fact that South Africa’s own nuclear weapons program, which the Carter administration was seeking to stop, was not yet sufficiently advanced to test such a weapon left just one prime suspect: Israel. Leading figures within the administration were therefore keen to bury the story and put forward alternative explanations.

Those alternative explanations were widely dismissed by many members of the scientific and intelligence community at the time; four decades years later, they look even more questionable.

On the 40th anniversary of the Vela event, Foreign Policy has assembled a team of scientists, academics, former government officials, and nonproliferation experts to analyze the declassified documents and data in the public domain, explain the political and strategic objectives of the key players at the time, and argue why a mysterious flash 40 years ago still matters today.

—Sasha Polakow-Suransky, deputy editor


Click the links to jump to each section

Part I: When America Caught a Nuclear Violator Red-Handed—But Stayed Silent —by Victor Gilinsky

Part II: From Sheep to Sound Waves, the Data Confirms a Nuclear Testby Lars-Erik De Geer and Christopher Wright

Part III: Politicians May Lie. The Archives Don’t. —by Avner Cohen and William Burr

Part IV: It’s Time for Jimmy Carter to Come Cleanby Leonard Weiss

Part V: How the 1979 Flash Might Test Us Yetby Henry Sokolski

Part VI: A Former Soviet Spy Remembers the Vela Incident: an Interview With Dieter Gerhardt —by Sasha Polakow-Suransky


When America Caught a Nuclear Violator Red-Handed—But Stayed Silent

by Victor Gilinsky

On Sept. 22, 1979, the U.S. Vela satellite  recorded the telltale light signal from a nuclear test using detectors called bhangmeters. The satellite, known as Vela 5B or Vela 6911, was one of a number launched in the wake of the 1963 Partial Test Ban Treaty (PTBT), which banned nuclear tests in the atmosphere, underwater, and in outer space. The detected signal was a “double flash” characteristic of nuclear test signals recorded on 41 previous occasions by Vela satellites.

A nuclear explosion light signal typically starts with a powerful millisecond-long light spike from the surface of the explosion’s dense early fireball, followed by a dark period of several milliseconds as the fireball expands and its surface temperature drops, and then a drawn-out powerful light as the expanding fireball becomes transparent and radiates a light signal from its interior as well. The signal is usually drawn on a graph using logarithmic scales on both axes, where it appears to have two comparable humps, hence a characteristic double hump. Nothing in nature produces such a double-humped light flash. The spacing of the humps gives an indication of the amount of energy, or yield, released by the explosion (see below).

The United States had launched the Vela satellites, orbiting as far as one-third of the way to the moon, to monitor compliance with the PTBT. Until 1979, they had not detected any illicit explosions among the 41 recorded nuclear events. The satellite in question, Vela 6911, had in fact been retired. Although not all of its systems were operable, the two principal light detectors were still functioning. It had previously distinguished itself mainly for detecting strong gamma-ray bursts from distant galaxies, an important scientific discovery. When it recorded a double flash in 1979, the signal could have come from anywhere within a diameter of several thousand miles.

Suspicion quickly fell on South Africa, which was known to be working on a bomb, and even more so on Israel, which had close military connections with South Africa and had an untested nuclear arsenal. U.S. President Jimmy Carter wrote in his diary for Sept. 22, 1979: “There was indication of a nuclear explosion in the region of South Africa—either South Africa, Israel using a ship at sea, or nothing.

An Israeli test would force him to deal not only with violation of the PTBT, but also with U.S. nonproliferation legislation. The 1977 Glenn Amendment to the Arms Export Control Act mandated an end to arms assistance, and an automatic application of extensive U.S. sanctions, if the president determined any state (other than the nuclear states authorized by the Nuclear Non-Proliferation Treaty) detonated a nuclear explosive after 1977. To complicate matters, the second round of Strategic Arms Limitation Talks between the United States and the Soviet Union was at that moment held up in the Senate, in part because of concerns about the United States’ technical capacity for verification. An inability to identify the culprit of the apparent nuclear test would strengthen the hand of the agreement’s opponents. 

The Carter administration set about developing a public relations strategy in case the information leaked. They believed their problems would go away if they could cast doubt on the satellite data. That is, if it could be argued there was no characteristic bomb signal, then there would have been no nuclear explosion, and therefore no need to do anything. That became the administration’s line.


In October, the president’s science advisor, Frank Press, a distinguished geophysicist but also an official tuned to his boss’s interests, set up a panel of scientific experts to examine the Vela event, and in particular whether the observed flash could have a non-nuclear explanation. The panel consisted of eight respected physicists and engineers, including a Nobel Prize winner, and was led by Jack Ruina, a professor at the Massachusetts Institute of Technology with long experience as a government advisor on weapons systems. 

The panel issued its final report in May 1980, after just three meetings. It concluded, “It is our collective judgment that the September 22 signal was probably not from a nuclear explosion.” Its members dismissed all evidence that suggested otherwise. This included the Naval Research Laboratory’s analysis that had located the blast’s ground zero near the Prince Edward Islands, about 1,000 miles from South Africa’s southern coast, using hydroacoustic (underwater sound) data, and claims regarding possible detection of radioactive iodine-131 in thyroids of Australian sheep, which if established could only have come from a bomb test (see following article). 

The prevalent view among White House insiders was clearly very different from the one they put out for public consumption. Carter, obviously influenced by the NRL’s analysis, wrote in his diary for Feb. 27, 1980: “We have a growing belief among our scientists that the Israelis did indeed conduct a nuclear test explosion in the ocean near the southern end of Africa.” 

Yet the panel decided to ignore both hydroacoustics and radioactivity, arguing that the apparent explosion-identifying signal could not be distinguished from the background “noise.” Its report did remark in passing, in reference to possible detection of radioactive products of nuclear fission, that “positive results from the debris collection effort would provide conclusive evidence of a nuclear explosion.” 

But instead of seriously evaluating the hydroacoustic and radioactive fallout data, as Lars-Erik De Geer and Christopher Wright would later do, the panel put forward at some length, a rather contrived alternative explanation—speculating that a micrometeor impact on the satellite might have ejected a shower of smaller particles that reflected sunlight in just the right way to mimic the light signal from a nuclear explosion. In the end, though, they did not stand behind it: “We do not maintain that this particular explanation is necessarily correct,” they wrote. Later analysis showed it was essentially impossible.

But for the Carter White House, all that mattered was the panel’s “probably not.” It classified key documents and closed the book on the subject. 

Perhaps the most important document it classified was the Naval Research Laboratory’s 300-page June 1980 report. The highly regarded research organization tasked several dozen staff members with an analysis of the hydroacoustic signals. 

While the NRL report remains classified, the gist of it can be gleaned from a Dec. 11, 1980 letter NRL research director Alan Berman sent to the White House after a futile attempt to draw the panel’s attention to his report. Berman was confident that the Navy’s sensors had indeed picked up the hydroacoustic signals of a nuclear explosion and that, taking into account the speed of sound in the ocean and the potential paths from the Prince Edward Islands, it came at a time consistent with the satellite observation of the light signal. According to Berman, “There was a large impulsive release of energy which coupled acoustic energy into the deep South Atlantic Sound channel.” Moreover, he wrote, the hydroacoustic signal stood out prominently from the random background noise.


The Carter administration was so afraid to enforce the PTBT against Israel’s 1979 violation that it did what it could to erase or keep hidden evidence of its detection of a test. Subsequent administrations, Republican and Democratic alike, went along with this, and the U.S. government still pretends it knows nothing about any Israeli nuclear weapons.

The longstanding U.S. refusal to acknowledge Israel’s nuclear arsenal has destroyed its credibility on nonproliferation.

It is an outcome—and a danger—that an arms control expert foresaw long ago. In the period before the PTBT, when the debate over nuclear nonproliferation agreements centered on the adequacy of technical means to detect Soviet cheating, Fred Iklé, in a classic 1961 Foreign Affairs article, reminded the arms control community that while technical means to verify performance are essential, compliance ultimately depends on a willingness to respond to detected violation. Iklé worried that, for political reasons, a democracy like the United States might decide to overlook an arms-control treaty violation. Most important, Iklé wrote, was to make sure a would-be violator could not expect to benefit from a violation. 

That’s not what happened after the Vela event. Israel’s nuclear program went on to acquire weapons deliverable by land, sea, and air, with the means of delivery provided by French-designed missiles, German submarines, and American airplanes. If anything, Israel’s nuclear weaponry gained a stronger political position vis-à-vis the United States. A June 2018 New Yorker article reported that Israel demanded, and got, secret letters from U.S. Presidents Bill Clinton, George W. Bush, Barack Obama, and Donald Trump, which Israeli leaders interpreted as a U.S. promise to protect their nuclear weapons. And indeed, these U.S. presidents did protect Israel’s nuclear weapons from scrutiny and criticism in the United Nations and other international forums. It is part of a pattern that has destroyed America’s credibility on nonproliferation. 

What Israel says—or doesn’t say—about its nuclear weapons is its own affair. But the United States should not agree to muzzle itself. It was always a humiliating role that opened the United States to the charge of hypocrisy. Now, in the face of strong confirmation of Israel’s violation of the Partial Test Ban Treaty, it has become an insupportable one. 


From Sheep to Sound Waves, the Data Confirms a Nuclear Test

An artist’s rendering of a Vela 5B satellite in orbit.National Security Archive

By Lars-Erik De Geer and Christopher Wright

Since the early days of nuclear weapons, there have always been forces trying to put the genie back in the bottle. That has proved difficult in a polarized world, but there have at least been a few partly successful attempts.

The first multilateral nuclear test ban was the Partial Test Ban Treaty, which outlawed tests of nuclear explosions in all environments except underground. It went into force in 1963, with the United Kingdom, the Soviet Union, and the United States as the original signatories. Within a few months, many other countries ratified it, including Israel and South Africa. 

Crucially, the Partial Test Ban Treaty regime didn’t include a system to verify compliance but relied on individual countries’ technical capabilities, some that were available to any state (such as atmospheric radionuclide surveillance) and some that were available only to a few (such as satellite-based detectors, known as bhangmeters, looking for optical flashes typical of nuclear explosions in the atmosphere).

The treaty has largely been respected by its member states. There was, however, one case that stood out. Exactly 40 years ago today, one such U.S. satellite detected a double flash of light that is typically emitted by nuclear explosions in the atmosphere.

This news was not welcomed by the U.S. government, because the most reasonable suspects were Israel and South Africa, two countries that the United States had delicate relations with at the time. The Camp David accords, catalyzed by U.S. President Jimmy Carter, were just a year old, and the United States was involved in intense negations with South Africa to persuade it to sign the Nuclear Non-Proliferation Treaty.

Indeed, one declassified document from the time lists options for what the U.S. government’s public posture should be on the Vela event; one of them was to “Emphasize that one cannot tell whether September 22 event was nuclear or non-nuclear.” Clearly, that option had an impact on the mandate of the panel appointed by Carter known as the Ruina Panel, which included the instruction to study whether the flash could have been “of natural origin.” 

In May 1980, the panel finished its report, and it was made publicly available in July. As requested, it delivered an alternative explanation: The flash could be solar light scattered into the bhangmeters’ view by debris ejected from a meteoroid impact on the satellite.

An intense debate followed in the scientific community with contributions from scientists at U.S. National Laboratories with expertise and deep knowledge of the technical matters. All potential corroborating information was rejected by the Ruina Panel—but the suspicion that the panel deliberately ignored key data for political reasons has not gone away.

We recently published two articles in the journal Science & Global Security that analyzed physical data about the Vela event that has become available in declassified documents. Original radionuclide data in the form of notebooks and ledgers from the laboratory of the late Lester VanMiddlesworth, who was in 1979 a professor at the University of Tennessee Health Science Center, that detected traces of iodine-131 in thyroid glands of sheep were also dug out from the Nuclear Testing Archive in Las Vegas. This enabled a new and independent analysis based directly on the raw data. 


Vela Records a Double Flash

The double flash signal recorded by the Vela satellite on Sept. 22, 1979, with the more sensitive bhangmeter’s reading on the bottom. The double flash, or double pulse, occurs because a nuclear explosion forms a dense fireball that radiates light from its surface. As it expands, its temperature drops, and so does the radiation. As it expands further, the radiation from the interior is able to escape, and the the brightness of the fireball increases again to form the second pulse, which peaks after about 100 milliseconds and then decreases when the whole volume cools down. As the first intense pulse is about 1 millisecond and the second about 100 milliseconds, both radiation and time scales have been modified for convenience in viewing. 1980 ruina Panel report

The first investigation dealt with the event-defining double-humped light pulse. Based on modern hypervelocity impact physics and several recently declassified documents, this new analysis showed the panel’s meteoroid collision hypothesis and variants of it to be much less likely than they might have appeared 40 years ago. 

The Ruina Panel noted that there was a discrepancy in the second, longer pulse between the more and the less sensitive bhangmeters onboard. This was essentially explained as an electronic background modulation artifact in papers written by relevant U.S. laboratories such as Sandia and Los Alamos before and after the Ruina report and declassified many years later. The conclusion in our 2017 research was that the nuclear explosion scenario had gained enhanced credibility and that the minimum and second maximum of the double pulse indicated an explosive yield of approximately 2 to 4 kilotons. 

The second paper focused on corroborative evidence from hydroacoustic and radionuclide observations. There was a strong signal detected from the south by hydrophones near Ascension Island that could be associated with an explosion close to the water surface at the time of the satellite’s detection of the double flash. The U.S. Naval Research Laboratory concluded that the likely explosion point was near the Prince Edward Islands in the South Indian Ocean, with the hydroacoustic signal echoed from the East Scotia Ridge, a prominent underwater ridge near the Antarctic in the South Atlantic. 

The Naval Research Laboratory carried out a detailed 300-page study that the Ruina Panel did not seriously consider at the time. It remains classified to this day, although useful information has become available in a declassified 1980 letter from the laboratory research director Alan Berman to the Executive Office of the President.  

Based on accepted models and experience from French nuclear testing in the Pacific Ocean, Berman concluded that the strong Ascension signals had been generated by an explosion near the surface of a fairly shallow part of the ocean and that the path length had been about 10,000 kilometers (6,200 miles). This gives an event time estimate less than two minutes before the flash and points quite persuasively to the waters around the Prince Edward Islands as the event location. 

Such sensitive measurements can be made because the temperature, salinity, and pressure gradients in the ocean form a kind of wave guide about 3,000 feet below the surface that allows sound waves to travel relatively unattenuated thousands of miles from their source; that is why whales can communicate at long distances.

The Vela bhangmeters’ field of view extended well into the Indian Ocean and past the Prince Edward Islands, but the searches for debris by special sampling aircraft were concentrated on the South Atlantic, which, given the strong westerly winds at the time, explains why no debris was detected. It was, rather, to be found in air masses heading from the Prince Edward Islands east toward Australia. 

Sheep slaughtered in Melbourne, Australia, had shown no evidence of nuclear exposure since the French nuclear tests in the South Pacific ended in 1974, but in October and November 1979 they showed signs of the short-lived fission product iodine-131.

No nuclear debris was detected from routine air samples in Australia and New Zealand. But it so happened that the Tennessee professor, VanMiddlesworth, had for decades collected thyroid glands from sheep and cattle around the world to study the uptake of radioactive iodine disseminated from nuclear tests in the atmosphere. This is an extremely sensitive method of detecting iodine fallout, as the thyroid gland very effectively absorbs iodine and sheep graze over large areas of land and are normally slaughtered shortly after the grazing season. 

The thyroid gland samples from sheep slaughtered in Melbourne, Australia, had shown no evidence of nuclear exposure since the French nuclear tests in the South Pacific ended in 1974, but in October and November 1979 they showed signs of the short-lived fission product iodine-131. It was not taken seriously by the Ruina Panel. 


Slaughtered Sheep and Underwater Sound Signals

The map on the left shows the position of Vela 6911 at the time of the flash and the tracks of the hydroacoustic waves that were picked up by hydrophones near Ascension Island and that indicated a source near the Prince Edward Islands. The strongest wave had bounced off the East Scotia Ridge while the direct wave was attenuated by bathymetric structures along the track. The map on the right shows meteorological trajectories at the 500-mbar-pressure level starting near the Prince Edward Islands and extending for nearly six days. The dark green fields in South Australia mark areas where there was some 5 mm rainfall on land during the cloud passage that produced the contaminated pastures that caused the concentrations of iodine-131 in sheep thyroids that were later detected in mid-October. The Prince Edward Islands are believed to be close to the detonation point, and Melbourne is the location of the abattoir that provided sheep thyroid glands to VanMiddlesworth.Lars-Erik De Geer

A few years ago, when VanMiddlesworth’s raw data was found stored at the Nuclear Testing Archive, a new and very careful analysis clearly showed the presence of iodine-131. Combined with meteorological transport calculations that show the paths taken by air from the Prince Edward Islands and the fact that 5 millimeters of rain had fallen when the cloud passed the southeast corner of Australia and the grazing fields of the sheep later slaughtered in Melbourne, the iodine detections became very strong corroborative evidence that Vela had detected a nuclear explosion. 

With the defining double pulse validated and the combined corroborative evidence from hydroacoustic and radionuclide detections, the latest analysis of raw scientific data that was dismissed in 1979 suggests that the Vela event was indeed a 2 to 4 kiloton nuclear explosion.


Politicians May Lie. The Archives Don’t.

This document prepared for a meeting of the Special Coordination Committee in 1980 weighed, in part, what the United States should reveal about its findings on the Vela incident.National Security ARCHIVE

By Avner Cohen and William Burr

The Vela controversy has continued for decades, but its details, involving sensitive scientific and political intelligence, remain mostly classified. In recent years, the state of the debate around the 1979 incident has changed dramatically. New detailed scientific analysis and new declassified documents have emerged in a manner that decisively support the view that the satellite known as Vela 6911 detected a nuclear detonation.  

Informing that view are a number of documents declassified in recent years, posted on the National Security Archive website, that reveal the high level of skepticism, anger and disagreement over the report from the U.S. government panel convened to study the incident, known as the Ruina Panel. We have published these documents in two electronic briefing books on the Vela incident, first in 2016 and then on the anniversary this month. In our view, the documents make clear that the true mystery of Vela is not whether the double flash showed a nuclear explosion but how top officials at the Carter White House collaborated to blur and conceal a politically uncomfortable truth. 

The archival files of Ambassador Gerard C. Smith, who served as a special presidential representative for nonproliferation matters from 1977 to 1980, were declassified in 2016. They include a great deal of new information on the Vela controversy within the U.S. government. Here are some of the highlights:

A secret CIA scientific panel. Within days after the Vela event, the CIA formed a three-man distinguished scientific panel—with Harold Agnew (a former director of Los Alamos National Laboratory), Richard Garwin (a former hydrogen bomb designer and senior scientist at IBM’s Watson laboratory), and Stephen Lukasik (a former director of DARPA and chief scientist at the Rand Corp.)—to review the Vela data. By October 10, they produced a preliminary technical document in which they agreed that the Vela “signals were consistent with detection of a nuclear explosion in the atmosphere,” but they also acknowledged that “the Vela sensor outputs were less ‘self-consistent’ than usual” (a reference to the fact that the two bhangmeters on the Vela satellite did not “yield equivalent or ‘parallel’ readings for the maximum intensity of the second flash.”) They noted that it was unusual to stage a test at night and that the measured yield, 1.5 to 2 kilotons, “was probably lower than the design yield.”

Richard Garwin’s initial view on the double flash. In a letter that Garwin sent to Deputy Director of the Arms Control and Disarmament Agency Spurgeon Keeny on Oct. 19, 1979, several weeks after the Vela flash, he maintained that “on the basis of the information which we obtained and the analysis we were able to do, I would bet 2 to 1 in favor of the hypothesis” that the incident was a nuclear explosion. He changed his mind while subsequently serving on the Ruina Panel, which Frank Press (Carter’s science advisor and director of the Office of Science and Technology Policy) and Zbigniew Brzezinski (Carter’s national security advisor) established later that month.  

The “Evening Report” intelligence briefing to National Security Advisor Zbigniew Brzezinski on Dec. 1, 1980. National Security Archive

Fallout in New Zealand and Australia. State Department telegrams from November 1979 reviewed efforts by New Zealand scientists who had reportedly detected small amounts of fallout in rainwater; the initial analysis was found to be a “false alarm,” and an official with the Air Force Technical Applications Center secretly confirmed that the data was “flimsy.” Nevertheless, by the end of 1980, the Defense Intelligence Agency had learned that the thyroid glands of sheep slaughtered near Melbourne during October 1979 showed “abnormally high levels” of iodine-131, a “short-lived isotope that occurs as the result of a nuclear event.” The sheep had grazed in an area where it had rained during Sept. 26 and 27, 1979. The Defense Intelligence Agency pledged to investigate whether the iodine could have been ingested as a result of nearby industrial or pharmaceutical activities. This is the first mention by the U.S. government of the data reviewed by the researchers Lars-Erik De Geer and Christopher Wright (see previous article), demonstrating that some parts of the U.S. government took the evidence seriously even while Carter’s appointed panel dismissed it. 

A declassified State Department memorandum included Varona’s statements, including his view that the Ruina report was a “white-wash, due to political considerations.”

The South African-Israeli nuclear connection. In 1977, the Carter administration was aware and concerned about Israeli-South African nuclear cooperation, but Israeli Prime Minister Menachem Begin denied any weapons development cooperation existed, while evading any questions about nuclear weapons development cooperation. At the end, Carter decided that “we shouldn’t push [the issue] any more for now.” 

Defense Intelligence Agency views on the Ruina report. According to Jack Varona, a senior Defense Intelligence Agency official, hydroacoustic data analyzed by the U.S. Naval Research Laboratory strongly indicated signals that were “unique to nuclear shots in a maritime environment.” The source of the signals was the area of “shallow waters between Prince Edward and Marion Islands.” The Naval Research Laboratory report is still unavailable, but a declassified State Department memorandum included Varona’s statements, including his view that the Ruina report was a “white-wash, due to political considerations.”


Notwithstanding the useful material in Smith’s files, most of the Vela archival record remains classified. For example, for decades rumors have circulated about relevant signals intelligence—communication intercepts—that were collected by the National Security Agency. But no signals intelligence material has ever publicly surfaced.

Furthermore, major Vela-related files in the Carter Library remain classified, although they have been requested for declassification review. Their release may probably provide a fuller and detailed picture of the Carter White House’s reaction to the Vela event, and especially the role and communication of both Brzezinski and Press. 

Recently disclosed informal comments by Brzezinski suggest why no one at the top was eager to pursue the Vela matter. On June 21, 2016, the writer Kai Bird, while working on Carter’s biography, sat with Brzezinski (eight months prior to his death) for a one-on-one broad conversation on Carter’s foreign policy. During that interview, Bird touched on the controversial Vela matter, almost in passing. According to Bird’s transcript:   

Kai Bird: Do you recall the intelligence issue over the Vela satellite?

Zbigniew Brzezinski: Oh, near South Africa?

Kai Bird: Near South Africa.

Zbigniew Brzezinski: Yeah. We knew something happened. We didn’t know precisely what happened. We had our suspicions. For political reasons, I think. I think. It wasn’t pursued to the very end because it wasn’t clear. Suppose we find out, what do we do then?

Kai Bird: And if it’s the Israelis, it becomes even more awkward.

Zbigniew Brzezinski: Well, that’s what I had in mind. Yeah.

While Brzezinski spoke rather vaguely, he seemed to admit that the Carter White House found the Vela issue awkward and that the result was a deliberate effort to avoid a comprehensive investigation. In the absence of documents, this admission is very important.   

It is worth noting that a previously released but heavily redacted CIA study from December 1979 titled “The 22 September 1979 Event” was written under the working assumption that the event was a nuclear explosion. 

The study examined the possibilities that either South Africa or Israel—or both jointly—conducted a nuclear test. The study’s “key judgements” are withheld, but it appears that the authors viewed Israel as the more likely perpetrator. The report ends its unredacted section on Israel by noting the following: “Indeed, of all the countries which might have been responsible for the 22 September event, Israel would probably have been the only one for which a clandestine approach would have been virtually its only option.” 

Incidentally, more than two decades later, one of us had a chance to discuss the Vela event with Stansfield Turner, the CIA director at that time. On that occasion, Turner said that he never “bought” the Ruina report and he had always accepted the prevailing view within the agency that the double flash was an Israeli nuclear test.


While no public smoking gun has surfaced that conclusively ties Israel to the Vela event, and no credible and identifiable Israeli source has ever openly confirmed an Israeli test, we believe, based on a great deal of documented and anecdotal evidence, that the Vela event was indeed the detection of a low-yield Israeli nuclear test consisting of the boosted primary stage of a two-stage hydrogen bomb—an atomic bomb sparking a thermonuclear reaction. The test was technically necessary to demonstrate Israeli mastery of that design. Here we summarize some of the circumstantial and anecdotal Israel-related evidence. 

Israeli nuclear program. What the aforementioned CIA study does not provide (at least in any of its released versions) is an assessment of the Israeli nuclear program in the mid-late 1970s and what the motivations for an Israeli decision to conduct a secret test were. During the 1973 Yom Kippur War, Israel’s biggest national trauma, the country appeared to be approaching the abyss. Top leaders and their nuclear advisors recognized that the country’s small nuclear arsenal—consisting of first-generation implosion (Nagasaki-style) weapons—was inappropriate and perhaps even irrelevant to the military situation in which Israel found itself during the early stages of the Yom Kippur War.  

Israeli leaders and their nuclear advisors recognized that the country’s small nuclear arsenal was inappropriate and perhaps irrelevant to the military situation in which Israel found itself during the early stages of the Yom Kippur War. 

This realization had a profound impact on the Israeli nuclear program in the post-1973 era. The Israel Atomic Energy Commission was carrying out a broad research and development program, with a focus on completing the mastery of two-stage thermonuclear weapons design. It was in this period that Shimon Peres, the man who is credited with the birth of the Israeli nuclear program in the late 1950s, took the role of defense minister and supported that push. A commitment to a two-stage design necessarily entails a need to test.

A high-level firing. Shalhevet Freier, the director-general of the Israel Atomic Energy Commission starting in 1971, was fired in 1976, and his replacement by Brig. Gen. Uzi Eilam was allegedly directly related to the preparations for the 1979 event—the implication being that the swap was due to Freier’s opposition to the test. Freier himself used to talk rather openly about his firing, stressing that it was not about “personal or moral conduct” and hinting that it was about a major policy issue about which he disagreed with his superiors, in particular Peres. Freier even suggested that his direct boss, Prime Minister Yitzhak Rabin, agreed with him on this classified policy issue, but for unrelated political reasons Rabin decided to defer to Peres and agreed to let Freier be fired. Freier, who died in 1994, never disclosed what the policy disagreement was.

A press leak from Israel. A CBS Evening News story about the Vela event on Feb. 21, 1980, was based on exclusive reporting from a young Tel Aviv-based American correspondent, Dan Raviv. The report claimed that CBS had learned that the Vela event was indeed an Israeli nuclear test. Raviv filed his report from Rome in an effort to evade Israeli military censorship. As a result, Raviv lost his press credentials after a direct order from then-Israeli Defense Minister Ezer Weizman. Decades later, Raviv told one of us that he had an additional high-level and reliable Israeli political source who confirmed the Vela story, the late Eliyahu Speiser, a well-connected Israeli politician and member of the Knesset for the Labor Party between 1977 and 1988. Speiser was in those days close to Peres.    

The MIT connection. Other documents in Smith’s file disclose that in February 1980, Jack Ruina, the chairman of Carter’s controversial panel and a professor at the Massachusetts Institute of Technology, received anecdotal information from a “personal contact” at MIT relating to the “theory of Israeli involvement” in the Sept. 22 event. The documents do not elaborate on what exactly that information was, but it is noted that Ruina considered it “significant but inappropriate for discussion on telephone.” It appeared that Ruina flew to Washington to discuss this information with Keeny and John Marcum, Frank Press’s executive secretary, who dismissed it as “speculative.” 

According to Seymour Hersh’s The Samson Option (published in 1991), Ruina’s source was an unnamed Israeli missile expert, who in 1980 to 1981 was a visiting fellow at MIT in a program that Ruina directed. That missile engineer was Anselm Yaron, as MIT records from that period indicate. Yaron was one of the founders of Israel’s weapons development authority, known as Rafael. 

While the White House dismissed Yaron’s information, Hersh’s suggestion that Yaron had implied that the Vela incident was an Israeli-South African test was corroborated to us by an individual who got to know Yaron well during his time at MIT. This individual recalled vividly an awkward moment around the spring of 1980, when Ruina gave a talk at MIT on the unclassified version of his panel’s report indicating that a test was unlikely. Yaron, who was in the audience, commented aloud on Ruina’s conclusions: “Don’t be too sure.”

The Naval Research Laboratory. Alan Berman had been director of research at the Naval Research Laboratory and played a crucial role in a June 1980 report that concluded that the preponderance of evidence based on a wide variety of data from specialized sensors, including underwater acoustic signals, supported a nuclear test. In the years that followed, when he was dean of the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, he became suspicious that the government of Israel was involved with South Africa in the conduct of the apparent test.

As dean, he met with many visitors in the physical sciences and “those from Israel always gently tried to steer the conversation toward what I may have detected,” he said. According to Berman, “they were very interested in what I knew about how to detect a nuclear explosion.” 

Even if the declassification process continues to hold back important intelligence reports and findings, the accretion of information, direct and circumstantial, makes the case for an Israeli nuclear detonation on Sept. 22, 1979, look more respectable than ever. 


It’s Time for Jimmy Carter to Come Clean

U.S. President Jimmy Carter signs the Nuclear Nonproliferation Act on March 10, 1978. Bettmann Archive/Getty Images

By Leonard Weiss

On Sept. 26, 1969, a fateful meeting occurred between U.S. President Richard Nixon and Israeli Prime Minister Golda Meir. No one else was present, but Nixon briefed Secretary of State Henry Kissinger afterward. The meeting took place at a time when the United States was urging membership in a universal treaty that, a few months later, formally became the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). 

Kissinger wrote a memo for the president on Oct. 7, 1969, that said: “You emphasized that our primary concern was that Israel make no visible introduction of nuclear weapons or undertake a nuclear test program.” In another memo, on Nov. 6, 1969, Kissinger recommends that “we not press the Israelis any further on this subject at this time.” On Feb. 23, 1970, Israeli Ambassador Yitzhak Rabin asked Kissinger to tell Nixon that Israel had no intention of signing the NPT and would regard any attempts to link arms sales to the treaty as “extremely unfortunate.” There was no recorded pushback by Nixon. And so the United States became an enabler of Israel’s policy of nuclear ambiguity, a policy adopted in essence first by President Lyndon B. Johnson, refined by Nixon, and sustained by every U.S. president since.  

The now-overwhelming evidence is that the tacit U.S.-Israel understanding that Israel would refrain from visible nuclear testing was violated on Sept. 22, 1979.


At the time of the Vela event, I was working in the Senate, specializing on nuclear policy matters. I was invited to briefings by Carter administration personnel that caused me to conclude that the Vela event was a nuclear test. The manner in which I was prevented from stating this opinion publicly caused me to conclude further that Israel was the perpetrator. 

The intelligence agencies at the time had little doubt that the signal was from a nuclear test. In an email on Oct. 18, 2012, H.T. Hawkins, who served as a senior scientist for global security at Los Alamos National Laboratory, described the intelligence community’s reaction at the time, using the Air Force’s reference for the event, A-747:

After we received the A-747 bhangmeter traces, [Defense Intelligence Agency] Director General Eugene Tighe asked me to hand carry them out to Los Alamos where I met Herman Hoerlin, who had led the development of the bhangmeter. Without being told anything about the origin of the two signals, Herman traced them with his finger like a maestro might look at a piece of music he had written. I asked him, “What do you think about these data?” 

“No doubt about it,” Herman responded, “An atmospheric nuclear explosion, several kilotons in yield, probably surrounded by lots of mass like a barge or the likes of it.”

I flew back to Washington and briefed General Eugene Tighe on Herman’s assessment. General Tighe looked at me and said, “Colonel, if that is the position of Los Alamos, then that will be the position of this agency.”

The Carter White House quickly went into crisis mode and clamped down on reports regarding the satellite information. President Jimmy Carter’s assistant secretary of state for congressional affairs was quoted as saying the State Department was in “sheer panic” over the Vela event and that Israel might be involved. Carter was planning to run for reelection in 1980, and the Vela event touched on several issues that could influence the public’s view of his record.

After all, Carter had been touting his support for nuclear arms control and nonproliferation. In his second debate with Gerald Ford during the campaign for the presidency in 1976, he advocated that “we move immediately as a nation to declare a complete moratorium on the testing of all nuclear devices, both weapons and peaceful devices; that we not ship any more atomic fuel to a country that refuses to comply with strict controls over the waste which can be reprocessed into explosives.” 

As president, Carter had taken a hard line toward Pakistan in 1977 and 1979, cutting off economic and military assistance because of Pakistan’s violations of laws forbidding the import of nuclear reprocessing technology and unsafeguarded enrichment technology. In addition to its requirements against reprocessing, the Glenn Amendment, passed in 1977, forbade nuclear explosive testing. Less than a year later, Carter would sign the Nuclear Nonproliferation Act of 1978—a law I took the lead in drafting while working on nonproliferation issues in the Senate—that was motivated by India’s 1974 nuclear test, under which nuclear trade with India would ultimately cease.

Carter also tried to forge a Comprehensive Nuclear-Test-Ban Treaty with the Soviets in the face of conservative political opposition claiming that verification of such a treaty was problematic and perhaps impossible. The Vela event presented several political dilemmas for Carter: If the administration claimed that Vela did not detect a nuclear test, then the disagreements from expert scientific observers of the satellite system would suggest a large element of uncertainty as to whether the satellite system for detecting nuclear explosions was reliable, which would translate into the unreliability of verification of a comprehensive nuclear testing ban.

On the other hand, if the administration admitted that Vela detected a nuclear test, then it would have to identify the perpetrator. If Carter named Israel as the perpetrator, he could not avoid the imposition of sanctions under the Glenn Amendment without declaring in essence that the United States had a double standard in its policy on nonproliferation and that Israel was subject to different rules than Pakistan and India. 

And imposing sanctions on Israel would have caused a furor among the large pro-Israel element in the Jewish diaspora, an important locus of political support for the Democratic Party and for Carter himself, especially after the success of his efforts to broker the Camp David Accords that brought peace between Israel and Egypt. 

Because the panel was kept from delving into intelligence information relevant to the Vela event, they could not consider whether reports of Israeli nuclear and missile cooperation with South Africa could have been motivating factors for a nuclear test involving both countries. The panel was tasked instead with searching for technical explanations of the double flash other than a nuclear test. 

In defense of the Ruina Panel’s conclusion, Richard Garwin has put forth arguments suggesting uncertainty in the Vela signal because of specific phase anomalies in the recorded bhangmeter data. These arguments have been countered by observers like Hawkins who contend that such anomalies were the result of aging of the bhangmeters and began to be seen so regularly that their appearance became a mark of authenticity in judging whether a test had occurred.  

While Carter did not lie about the Vela event, he allowed the truth to be obscured by means of a White House panel whose creation was politically motivated.

The sensitivity of the U.S. government on the subject of Israel’s nuclear weapons is such that federal employees with security clearances are still today regularly admonished to refrain from publicly discussing Israel’s nuclear capabilities, as I was in 1979, and this wall of silence extends to subsequent presidential administrations. As a result, the full political ramifications of an Israeli test have been avoided thus far. After four decades, there is a constituency within government, arms control think tanks, and political organizations for letting sleeping dogs lie. 

In the age of President Donald Trump, it is natural to avoid raising an uncomfortable issue that is now 40 years old when there are virtually daily assaults on the U.S. Constitution and the liberal international order. But if there is any hope of a successful international movement toward a world without nuclear weapons there must be a serious commitment to the enforcement of international treaties, regardless of the diplomatic or domestic political problems such enforcement might create.

Carter famously ran on a promise of never lying to the American people. While Carter did not lie about the Vela event, he allowed the truth to be obscured by means of a White House panel whose creation was politically motivated. In his golden years, he should consider setting the record straight as yet another important contribution to his legacy as a peacemaker committed to nonproliferation. 

Correction, Sept. 22, 2019: An earlier version of this article misstated the number of members of the Ruina Panel who are still alive.


How the 1979 Flash Might Test Us Yet

North Korean leader Kim Jong Un inspects the ground jet test of a newly developed high-thrust engine at the Sohae Satellite Launching Ground in North Korea in a photo released by state media on March 19, 2017. STR/AFP/Getty Images

By Henry Sokolski

Even when awkward facts are generally known—and perhaps especially when they are—getting government authorities to admit to them is difficult. U.S. officials have so far refused to confirm that Israel conducted atmospheric nuclear tests off the South African coast in 1979, and with good cause. 

Admitting Israel did so could not only trigger U.S. legal sanctions, but affirm Israeli violation of the Partial Test Ban Treaty, which Israel ratified in 1964. Although it might be distasteful and galling for the U.S. government to now admit that it should have confirmed the Israeli nuclear test long ago, the national-security hazards of not doing so—think Iran and other near-nuclear weapons states violating their nuclear pledges—would be worse.

To its credit, the Trump administration has made treaty enforcement the sine qua non of U.S. participation in international nuclear limitation agreements. In its Nuclear Posture Review, it emphasized the importance of effective compliance, enforcement, and enforceability of nuclear arms controls as a condition for U.S. support. Not long after the review’s publication, the administration withdrew from the nuclear deal with Iran, noting Tehran had violated its terms regarding heavy-water production and inspection of military sites. 

Then, several months later, U.S. President Donald Trump withdrew from the Intermediate-Range Nuclear Forces Treaty. The Russians, he argued, fielded missiles that were in clear violation of the agreement. Now, there is talk that the administration may not extend its New Strategic Arms Reduction Treaty with Russia. The House Foreign Affairs Committee, however, has drafted bipartisan legislation urging the administration to continue the treaty “so long as it maintains the strongest possible enforcement.”

Even if the U.S. government is today exceptionally attentive to nuclear compliance, it wasn’t always. In 1979, to override the Central Intelligence Agency’s early determination that Israel had likely conducted nuclear testing, the White House immediately formed a panel of experts to come up with an “alternative explanation” for the worrying Vela satellite readings. The panel actually didn’t come up with an explanation it thought was very likely, but it nonetheless concluded the satellite observation “probably” was not nuclear in origin. That seemed good enough. 

Nor were the Nixon, Ford, or Carter administrations all that perturbed by India’s 1974 violation of its pledge not to use U.S. nuclear exports (in this case, heavy water) to make bombs. When India used “peaceful” U.S. and Canadian nuclear assistance to build its first nuclear weapon in 1974, Canada cut off further nuclear exports. The United States did not. Instead, the State Department concluded that India’s test did not violate any U.S. agreement, lied to Congress about India’s use of American heavy water, and continued U.S. nuclear fuel exports to New Delhi. 

More recently, U.S. President George W. Bush looked the other way when the International Atomic Energy Agency found evidence that South Korea and Egypt were in breach of its nuclear safeguards obligations. Trump’s recently ousted national security advisor, John Bolton, who was then under secretary of state for arms control and international security affairs, urged his superiors to refer the South Korean case to the United Nations Security Council. He was quickly overruled.

Given the mounting evidence, including the most recent analyses relating to the 1979 explosion’s radioactive fallout, the question now is whether the the U.S. government might finally share what it knows about the event. This would seem to make sense, as it would help discourage future violations of pledges not to test by countries such as Iran, Saudi Arabia, Egypt, Turkey, South Korea, Japan, and other aspirational nuclear states. 

The bureaucracy isn’t likely to back it, though. Although the Trump administration is a stickler for compliance and enforcement of nuclear understandings and treaties, Israel is a special case. Every U.S. president since Richard Nixon has refused to acknowledge Israel had a serious nuclear weapons program or arsenal. It would be risky at best for any U.S. official’s career to confirm Israel should be shamed as a violator of an international nuclear agreement it signed and ratified. That, after all, is what Israel accuses Iran of doing. 

Then, there are the legal implications of a violation confirmation. In 1976, 1977, and 1994, U.S. senators succeeded in securing legislation known as the Symington and Glenn amendments. These laws banned U.S. foreign, financial, or military assistance to any countries—apart from the five nuclear weapons states under the Nuclear Non-Proliferation Treaty—that acquired uranium enrichment or nuclear reprocessing technologies or who set off a nuclear device. 

Of course, the law allows the president to waive these sanctions, but Israel, which receives billions of dollars in U.S. assistance, would hardly welcome such treatment. This would be doubly so if Trump should persist in pushing a formal mutual security pact with Israel; Israel’s critics would have a field day.

Still, if the president is asked whether Israel has nuclear weapons or has ever tested them, he might just blurt out the truth. And, then, there is the prospect of a progressive Democratic president who, eager for more nuclear controls, might add to what former U.S. President Jimmy Carter has already confirmed regarding Israel’s nuclear program. With time and increasing evidence that Israel did test in 1979, the odds of confirmation only increase. 

The question is just when such a confirmation will be made. Will it come before an Iran or South Korea, a Turkey or Egypt or Saudi Arabia, treat Israel’s violation as precedent and take comfort in the United States’ denials to ease their way toward testing themselves? Or will it come later, when the last vestige of nuclear constraints, including the Nuclear Non-Proliferation Treaty and the Partial Test Ban Treaty, have fully fallen into disuse and decay? If so, a return to order may require nothing less than the kind of political shock that came in 1945 with the nuclear bombing of Hiroshima.


A Former Soviet Spy Remembers the Vela Incident: an Interview With Dieter Gerhardt

The naval corvette SAS Amatola sails past central Cape Town, South Africa, on its way to the the naval base in Simonstown in November 2003. JOHN SVERDLOFF/SA NAVY NEWS/AFP/Getty Images

by Sasha Polakow-Suransky

Dieter Gerhardt was appointed as commanding officer of South Africa’s Simonstown dockyard a few weeks after the Vela incident in 1979. Previously, he had been a senior officer working on force development under the South African Defense Force’s chief of staff for operations. He was, at the time, also a high-level Soviet spy working for the GRU military intelligence service. Foreign Policy spoke to him via email about his recollections of the Vela incident.

Foreign Policy: Simonstown naval base was closed for a few days around the time of the Vela incident. Were you given any explanation at the time—and where did the order to close come from?

Dieter Gerhardt: No direct explanation was given. Orders came directly from the [defense] minister’s office. Often one can deduce that an activity is highly confidential when senior responsible officers are extremely tight-lipped and dodge seemingly reasonable questions.

FP: When South Africa was caught preparing an underground nuclear test in 1977, you played a role in tipping off the Soviets, whose satellite detected the test preparations. In 1979, do you remember any of the people involved in South Africa’s nuclear program reacting to news of the double flash?

DG: Individuals involved in the program disappeared from the scene and were isolated from their previous colleagues. The brightest of the bright were suddenly no longer reachable. The gaps left by their sudden absence told a significant story itself.

FP: Do you recall any Israeli ships visiting Simonstown in the months before or after September 1979?

DG: A visit by Israeli vessel was not noticed or recorded. Visiting ships of another so-called pariah state were present, i.e., Taiwan. The significance of that is not known to me.

FP: Do you think Israel could have carried out an atmospheric nuclear test completely on its own?

DG: It is entirely possible for Israel to have conducted the test on its own without South African direct participation other than giving the go-ahead for the test to be carried out in the region and giving normal ship support such as fuel, water, and vittles. I do believe, however, that this was a joint project from which South Africa’s own nuclear program would have benefited.

Dieter Gerhardt, a former commodore in the South African Navy, on Sept. 3, 1992.Michael Kupferschmidt/Keystone/AP

FP: Are there any facilities on the Prince Edward Islands?

DG: Facilities on island are limited to a small research station. No landing strip as such. Helicopter pad perhaps for South African research vessels’ infrequent visits to drop off and collect researchers.

FP: The CIA report on the Vela event suggests that it could have been done by two to three medium-size ships and a few dozen people. How could South Africa provide “normal ship support” to such Israeli ships?

DG: Transfer at sea—a normal exercise for support logistic and refueling activity. But it’s unlikely that the Prince Edward Islands were used as a support or jump-off point. They take ships several days to reach from Simonstown.

FP: Did you ever meet Ezer Weizman, who was Israeli Defense Minister from 1977 to 1980, during your trips to Israel—and did you ever see him in South Africa?

DG: I never met Weizman and do not know of his movements. The only individual of significance that I met was Uzi Eilam [the director of the Israeli Atomic Energy Commission from 1976 to 1986], but no discussion on nuclear matters took place between us.

FP: In what context did you meet Uzi Eilam?

DG: I was tasked by the minister of defense (at that time P.W. Botha), I think in 1975 to take Uzi and his wife, Naomi, on a familiarization, R&R trip around the country. No aspects related to the topic were mentioned during the duration of the week’s tour.

FP: How did the Soviets react to news of the 1979 double flash? Did they suspect Israel was behind it—and were they concerned or threatened by Israeli testing?

DG: I have no idea how the USSR reacted. They were well informed on many aspects of the South African nuclear program and were certainly concerned about proliferation—to the extent that observation satellites were launched and U.S. authorities alerted [when underground test preparations were detected in 1977]. They were fully aware of the close military ties between South Africa and Israel and many of the joint projects being conducted.

FP: In the 40 years since the flash, has anyone within South African military or intelligence circles ever said anything to you suggesting that they personally observed or had knowledge of the Sept. 22 event?

DG: No, not a peep! Military personnel would not have been directly involved. Perhaps [the state arms manufacturer] Armscor or Atomic Energy Board personnel were.

William Burr is the director of the Nuclear Documentation Project at the National Security Archive at George Washington University.

Avner Cohen is a professor and senior fellow at the Middlebury Institute of International Studies at Monterey and a global fellow with the Wilson Center. He is the author of Israel and the Bomb and The Worst-Kept Secret: Israel's Bargain With the Bomb. Twitter: @avnercohen123

Lars-Erik De Geer is a retired official from the Swedish Defense Research Agency and served on the preparatory commission for the Comprehensive Nuclear-Test-Ban Treaty Organization.

Victor Gilinsky, a physicist, was a commissioner of the U.S. Nuclear Regulatory Commission during the Ford, Carter, and Reagan administrations.

Sasha Polakow-Suransky is a deputy editor at Foreign Policy and the author of The Unspoken Alliance: Israel’s Secret Relationship with Apartheid South Africa. Twitter: @sasha_p_s

Henry Sokolski is the executive director of the Nonproliferation Policy Education Center and the author of Underestimated: Our Not So Peaceful Nuclear Future. He served as deputy for nonproliferation policy in the office of the U.S. secretary of defense from 1989 to 1993.

Leonard Weiss is a visiting scholar at Stanford University’s Center for International Security and Cooperation, and a former professor of applied mathematics and engineering. For over two decades he was Sen. John Glenn’s staff director at the U.S. Senate Committee on Governmental Affairs. He was the chief architect of the Nuclear Nonproliferation Act of 1978 and the Glenn Amendment of 1977.

Christopher Wright is an associate professor of Physics at the University of New South Wales, Canberra.