No, Iron Dome does not prove that "Star Wars" was right.
- By Yousaf Butt<p> Yousaf Butt is a nuclear physicist who serves as a scientific consultant for the Federation of American Scientists. The views expressed are his own. </p>
Israel’s "Iron Dome" missile defense has been spectacularly successful at intercepting short-range Hamas rockets: officials relate that roughly 80-90 percent of attempted intercepts have succeeded. However, it is important not to learn the wrong lesson from this. Some have gone so far as to claim that Iron Dome’s success finally vindicates Reagan’s dream of a missile defense "shield" against nuclear-tipped ICBMs. That this small battlefield system has been so successful against the relatively slow-moving short-range rockets doesn’t mean that larger and much more expensive missile defense systems, such as the planned NATO system, will work against longer-range strategic missiles that move ten times as fast.
Besides the speed of the quarry, there are two important distinctions between the systems: where the intercepts take place (in the atmosphere for Iron Dome vs. in space for the NATO system), and the nature of threat (conventional battlefield weapons vs. nuclear-tipped deterrent arms).
According to the current NATO missile-defense plan, the United States, working with European allies, would ramp up the deployment of a mix of increasingly sophisticated sea- and land-based missile interceptors around Europe in an attempt to guard against any possible future Iranian nuclear missiles. While this certainly sounds good, the problem is that an enemy intent on delivering a nuclear payload could easily defeat the NATO system by using decoy warheads, thereby swamping the defense’s radars and other sensors with fake signals.
In contrast to the short-range Hamas rockets, which fly through the atmosphere during their whole trajectory, the longer-range ballistic missiles — which the NATO missile defense system is designed to counter — spend most of their flight in space. For decades it has been known that trying to intercept a warhead in space is exceedingly difficult because the adversary can use simple, lightweight countermeasures to fool the defensive system.
For instance, cheap inflatable balloon decoys — similar to the shiny ones at children’s birthday parties — can be released together with the warhead when the missile burns out. Because the NATO missile-defense interceptors try to strike the warhead in the vacuum of space, these balloons and the warhead travel together, making it impossible to distinguish the decoys from the real thing. If many such lightweight balloons were released near the warhead, the defense would quickly be overwhelmed with fake targets.
In fact, the CIA’s own top specialist in strategic nuclear programs testified in 2000 that "[m]any countries, such as North Korea [and] Iran … probably would rely initially on readily available technology … to develop penetration aids and countermeasures. These countries could develop countermeasures based on these technologies by the time they flight test their missiles."
Unfortunately, warnings of such fatal weaknesses were not heeded in designing the NATO missile defense system. Now, two government-sponsored scientific studies have shown that the missile defense system being planned to protect the United States and Europe is fundamentally flawed and will not work under combat conditions. As Philip Coyle, who was associate director for national security and international affairs in the Obama administration’s Office of Science and Technology Policy, recently put it, the program is "chasing scientific dead ends, unworkable concepts and a flawed overall architecture."
The Pentagon’s own Defense Science Board report on NATO missile defense says that "the importance of achieving reliable . . . discrimination [between the warhead and decoys] cannot be overemphasized." It underlined that missile defense is "predicated on the ability to discriminate" real warheads from other targets, "such as rocket bodies, miscellaneous hardware, and intentional countermeasures." And if "the defense should find itself in a situation where it is shooting at missile junk or decoys, the impact on the regional interceptor inventory would be dramatic and devastating!" In short, the interceptor inventory would be exhausted in chasing decoy warheads, rendering the system useless.
Both because they are about ten times slower than long-range missiles and because they fly through the atmosphere, the Hamas rockets are much easier to intercept. Any decoys would quickly slow down in the atmosphere and be rendered ineffective and so none are used. So extrapolating the success of Iron Dome to the NATO system is technically unwarranted — they are entirely different beasts.
Another big difference between Iron Dome and the NATO missile defense system is the nature of the threat. Iron Dome guards against small battlefield rockets that are actually used, whereas the NATO missile defense system is designed to counter nuclear-tipped missiles that are useful for their deterrent value and that have never actually been used since they were invented. Such missiles are intended to protect one’s own nation and influence adversaries’ strategic calculations; they are not fired off in everyday battles.
So an 80 percent-effective tactical missile defense system against conventional battlefield rockets — such as Iron Dome — makes a lot of sense. If 10 conventional rockets are headed your way, stopping eight is undeniably a good thing. The possibility of stopping eight of 10 nuclear warheads, however, is less decisive in altering strategic calculations since even one nuclear explosion will inflict unacceptable devastation. Just one nuclear-tipped missile penetrating your missile shield is about the equivalent of a million conventional missiles making it through. An imperfect — or, as is the case in the NATO incarnation, a deeply flawed — missile defense system doesn’t alter the deterrent calculus between states. At least, it shouldn’t.
So even after NATO has set up and activated a strategic missile-defense system, it still will not have neutralized the perceived threat from Iran — if and when Tehran obtains nuclear weapons — or North Korea. Not only that, but Washington’s strategic calculations toward our adversaries will remain unaffected: The United States will still need to be just as worried about Iran’s missiles, since the destruction of even one NATO city or region is simply too high a cost to bear. For that security calculus to change, national missile defense would need to intercept 100 percent of incoming nuclear warheads. This is an unattainable goal for any piece of machinery, and especially for the system being fielded, given the government’s own damning scientific assessments.
As Pavel Podvig succinctly put it, "it would take only a small probability of success to make such a [nuclear] threat credible while missile defense would need to offer absolute certainty of protection to truly be effective." Even the largely successful Iron Dome system, while providing a worthy cover has not provided normalcy for Israeli citizens: the terror is still there.
A defense against deterrent nuclear-tipped missiles could also backfire by causing our adversaries to pre-emptively increase the number of missiles in their stockpile. So while the NATO system creates incentives for NATO adversaries and competitors, including Russia and China, to increase their nuclear stockpiles, it offers no credible combat capability to protect the United States or its allies from this — increased — weaponry.
And if policy makers mistakenly believe that the strategic missile defense system can protect them from nuclear attack, they may stake out riskier policies than they otherwise would. In fact, it is possible that the protection afforded by Iron Dome may have played a role in encouraging Israel to escalate the recent conflict, secure in the system’s effectiveness. A similar escalation, but with a dysfunctional missile defense system, may lead to a much more dire nuclear miscalculation.
But what if a system could be invented that did offer a high degree of protection from long-range nuclear missiles? Unfortunately, such a system would only encourage a change in the delivery method of the nuclear weapons used by our adversaries. It would not devalue the nuclear weapons themselves.
A "functional" missile defense to counter North Korea’s ICBMs, for example, could encourage Pyongyang to develop a ship-borne nuclear device instead. Since such a weapon is more difficult to detect and attribute to a given country, our adversaries may be less inhibited in using it as compared to an easily detected ICBM, which has a clear point of origin. (U.S. satellites continually monitor the globe for missile launches.) So if a missile defense encouraged our adversaries to exchange even a single ICBM for a ship-borne one, our security would actually decrease. Of course, an adversary might develop these alternate delivery methods in any case, but creating incentives for them to do so is not in our interest.
In short, if our adversaries obtain nuclear weapons, we should actually hope that they are mounted on missiles, because missiles are attributable — we can pinpoint their launch sites — and thus our enemies are deterred from using them. The real danger of a strategic missile defense that works is that it may work to discourage the missiles — without discouraging the nuclear weapons themselves.
The real lesson in all this is that we should work hard to stop the spread of nuclear weapons — once our adversary has them, we will be deterred no matter what kinds of defenses we think we have. But to stop the spread of nuclear weapons we need the assistance of major players like Russia and China. Ironically, the infatuation with the NATO missile defense ensures that we don’t get that cooperation because those nations may fear that the system alters the strategic balance with the United States. Indeed, the bipartisan Strategic Posture Commission has pointed out that "China may already be increasing the size of its ICBM force in response to its assessment of the U.S. missile defense program."
Although Iron Dome has been remarkably successful in intercepting slow-moving battlefield rockets in the atmosphere, one ought not jump to conclusions about what this means about attempting to defend against high-speed nuclear missiles in space — or even its desirability.