Electromagnetic Pulses Are the Last Thing You Need to Worry About in a Nuclear Explosion

One of America’s weirdest strategic obsessions won’t go away.

A surface test of a nuclear device in Nevada
A surface test of a nuclear device in Nevada circa 1955 shows the beginning of a mushroom cloud. Bettmann Archive/Getty Images

It is hard to pinpoint what, specifically, the electromagnetic pulse did to the electronic infrastructure of Hiroshima, Japan, on Aug. 6, 1945. In the days and months after the blast, the first use of a nuclear weapon in war, electrical power remained out in the city. If no specific attention was paid to the particular way that part of a nuclear blast interacts with the electrical grid, it is because the effect of the weapon was total and horrific. Amid the rubble, the radiation, the fire and ruin and mass death, fried electronics were barely noticed.

The electromagnetic pulse that comes from the sundering of an atom, potentially destroying electronics within the blast radius with some impact miles away from ground zero,  is just one of many effects of every nuclear blast. What is peculiar about these pulses, often referred to as EMPs, is the way the side effect of a nuclear blast is treated as a  special threat in its own right by bodies such as the Task Force on National and Homeland Security, which, despite the official-sounding name, is a privately funded group. These groups continue a decadelong tradition of obsession over EMPs, one President Donald Trump and others have picked up on. These EMP-specific fears are wholly divorced from the normal risk calculations of a war between nuclear-armed states and the threat of nuclear oblivion. Doing so obscures the history—and misunderstands the dangers.

EMPs were anticipated before they existed. Enrico Fermi of the Manhattan Project hardened sensors at the Trinity test site so that the detonation would remain useful science. Later nuclear tests would look at the way this pulse risked disabling other warheads in flight, and what would happen if a warhead was detonated so high above Earth that the pulse was its primary effect.

For the early planners of the apocalypse, the greatest risk posed by an EMP was to nuclear warheads themselves. Strategic planning called for multiple warheads to obliterate a city, and the engineers were worried about what might happen if the first nuke to explode disabled the electronics inside the other warheads, causing them to land inert instead. This was called “warhead fratricide,” and researchers at the Lawrence Livermore National Laboratory ran Monte Carlo simulations to estimate the odds.

Once understood, the problem of nuclear weapons disabling other nuclear weapons was solved, primarily, by engineering around the known parameters of EMPs. Hardening electronics, with special shielding that directs current around sensitive parts of machines, has been a staple of nuclear weapon design for decades. It is a known, solvable problem. The U.S. Department of Defense absolutely requires hardening for military electronics critical to nuclear command and control, while standards exist to harden other electronics, as well as civilian infrastructure that the military depends on for non-nuclear threats.

That hasn’t stopped it becoming a perpetual bugbear of strategists. Then-Rep. Trent Franks argued before Congress in 2012 that terrorists might acquire and then use a nuclear weapon to create an EMP. The logic goes like this: A nonstate actor simultaneously in possession of a nuclear weapon, a missile, and a freighter brings all three close to a port in the United States. Then, that terrorist group uses the missile to loft a nuke into space above the United States, detonating it, causing an electromagnetic pulse that wipes out electronics across the country.

This Rube Goldberg-style fear is dependent not only on a catastrophic failure of intelligence, but also on the group in possession of the nuke exercising a strange logic themselves. Why, after obtaining a nuclear weapon, would they not simply use the blast to kill hundreds of thousands of people directly? Franks argued that the American dependence on modern technology poses a unique vulnerability enemies might exploit, unlike the common vulnerability every human being has to their flesh being disintegrated by fire and heat.

High-altitude nuclear EMPs were discovered as part of the atmospheric Operation Fishbowl testing series in 1962. The most famous of these, Starfish Prime, was detonated at nearly 250 miles above the planet’s surface. The electromagnetic pulse was far-reaching, shutting down some streetlights in Oahu almost 900 miles away from the detonation. The partial test ban treaty of 1963 meant that the Fishbowl series were the last live explosion high-altitude tests by the United States, but the potential of using a nuclear weapon blown up high in the sky to disable electronics became a dedicated part of nuclear war planning for ever afterward.

By the 1970s, EMP effects were fully incorporated in the U.S. planning about nuclear war. Following the broadcast of the TV special The Day After in 1983, New York Times columnist John Corry launched EMP concerns into the public eye by specifically worrying that an EMP could wipe out U.S. second-strike capabilities. In response, Richard Garwin, who in 1954 wrote one of the first theoretical papers at the Los Alamos National Laboratory on the origin of EMPs from nuclear explosions, sought to dispel the unique fear of EMPs in a letter to the editor published by the Times.

“Since 1962, the delicacy of some electronics has increased because of the use of transistors and integrated circuits, but our understanding of electromagnetic pulse has matured so that specific equipment and systems can be tested and guaranteed against disruption by EMP,” Garwin wrote.

This hardening included the communication links for the nuclear chain of command and the hardening of the silos and aircraft themselves against the dangerous effects from the pulse. That some electronics would fail in the event of a high-altitude EMP attack on the United States did not mean that the whole of the nuclear enterprise would be rendered inert, no matter how many hyperbolic pronouncements claimed it would be a Pearl Harbor-style event

“Furthermore,” Garwin continued, “it is inconceivable that the Soviet Union would use nuclear weapons only to produce electromagnetic pulse; many nuclear warheads would attack bomber bases and other vulnerable military targets; EMP would be the least of our problems at the outbreak of nuclear war.”

Garwin’s letter came at a time when the primary concern of the U.S. nuclear enterprise was preparing for, and deterring, a war with the Soviet Union. That arsenal, now Russian, remains the primary concern of nuclear forces. Russia, like the United States, maintains a standing arsenal of over 1,500 deployed nuclear weapons. That’s the scale where, should either country decide to launch a nuclear attack, a warhead or three could be spared to create a high-altitude EMP effect against another country without significantly reducing the total harm caused by the more familiar blasts and pressure waves of nuclear detonation. The destruction to electronics, as in Hiroshima, would be a very low-level concern compared to the charred bodies of children and cities on fire.

For the rest of the nuclear-armed world, with total arsenals estimated at between 35 to 320 warheads, using one of them for an EMP effect makes even less strategic sense.

What is known about nuclear weapons is the damage they cause to people, to cities, and to physical objects from physical force. These are the effects that haunt our understanding of Hiroshima and Nagasaki. A nuclear blast is an unsubtle form of harm. Focusing on EMPs outside the context of a broader nuclear war assumes a wholly unique strategic calculus, one that sits outside any understanding of war or even terrorism. It ascribes nearly supernatural powers to electronics and the threatened loss thereof. And it assumes that detonating a nuclear weapon in orbit over a country would not be met with the same immediate and hostile reaction as detonating a nuclear weapon in a city.

To fear the EMP is to look at the vast military strength of the United States, and see, as Franks did, that strength as a surrogate for a unique vulnerability. It is to imagine that the United States has built itself an Achilles’ heel, one that when pricked will lead to the collapse of all of Western civilization.

“Such EMP weaponry could also be deployed with only slightly more advanced means from space to rip up the electrical and electronic infrastructure of the American homeland,” testified the physicist Lowell Wood, then at Lawrence Livermore National Labs, before Congress in 1999. “Thus, the de facto national policy of nakedness to all of our potentially EMP-armed enemies takes on ever more of the character of national-scale masochism. It is perverse and irrational, and it is assuredly not necessary or foreordained.”

That is a lot to unpack, but it is emblematic of the public fight over EMPs. There is nothing uniquely American about not wanting to die in a fiery inferno. But there was, at least for a time, an idea that alone among nations, the United States would be unable to function without telephone lines or a functioning power grid. If Congress could be convinced that this was true, it could justify almost any action as a preemption against the threat, from benignly hardening the grid to dangerously launching new wars against states with nuclear weapons programs.

Nuclear war is a serious threat. It has been for decades, however much we might want to forget about it. But the idea of a nuclear weapon creating an EMP without immediately sparking a nuclear war is entirely laughable.

Correction, July 22, 2020: A previous version of this article contained an image caption that incorrectly described a photograph of a nuclear test. The caption has been updated to accurately reflect the image.

Kelsey D. Atherton is a defense technology journalist based in Albuquerque, New Mexico.

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