05/08/2010 - 07:49

The myth of missile defense as a deterrent

Yousaf Butt

Yousaf Butt

Butt is a research professor and scientist-in-residence at the James Martin Center for Nonproliferation...


The Obama administration's long-awaited Nuclear Posture Review (NPR) "establishes U.S. nuclear policy, strategy, capabilities and force posture for the next five to ten years." The review signals a fresh approach to nuclear doctrine; however, its reliance on missile defense as an element of nuclear deterrence is wrong. Such systems are useless, dangerous, and destabilizing, and ramping up reliance on missile defenses because of planned reductions to the U.S. operational nuclear stockpile is deeply misguided.

Specifically, the new NPR states, "Nuclear forces will continue to play an essential role in deterring potential adversaries and reassuring allies and partners around the world. But fundamental changes in the international security environment in recent years--including the growth of unrivaled U.S. conventional military capabilities, major improvements in missile defenses [emphasis added], and the easing of Cold War rivalries--enable us to fulfill those objectives at significantly lower nuclear force levels and with reduced reliance on nuclear weapons."

In other words, the posture review essentially asserts that missile defense can somehow compensate for the deterrent capability that will supposedly be lost due to reductions in the U.S. nuclear stockpile. Setting aside the fact that there haven't been any realistic tests indicating "major improvements in missile defenses," such logic is questionable on three levels.

First, it's far from clear that the precise number of deployed U.S. nuclear weapons affects an adversary's deterrent calculus--especially when the operational stockpile will still consist of more than 1,000 weapons. (Even if New START is ratified and the Russian and U.S. operational warheads are reduced to about 1,550 each, many thousands of additional weapons will remain in the reserve stockpiles.) As Jeffrey Lewis has pointed out, "An enemy who can be deterred, will be deterred by the prospect of a counterattack, even if it consists of only a few nuclear weapons. Beyond that minimum threshold, nuclear weapons provide little additional deterrent benefit." Similarly, Col. B. Chance Saltzman, chief of the air force's Strategic Plans and Policy Division, has argued that "the United States could address military utility concerns with only 311 nuclear weapons in its nuclear force structure while maintaining a stable deterrence." So contrary to what the NPR indicates, slightly reducing the U.S. operational arsenal won't create a "deterrence gap" that needs to be filled.

Second, even if reducing the U.S. stockpile did affect U.S. deterrent posture, missile defense couldn't replace any lost deterrent value because missile defense doesn't deter nuclear attacks. The purpose of missile defense is to defend--or, more accurately, attempt to defend. An adversary wouldn't be deterred from launching a nuclear attack because of the existence of missile defense; rather, it's the credible threat of overwhelming nuclear retaliation that deters an adversary. If the enemy is irrational and suicidal enough to discount the threat of massive nuclear retaliation, then a missile defense system that can theoretically intercept only some of the attacking missiles most certainly isn't going to be a deterrent. In wonk parlance, the NPR conveniently conflates reprisal deterrence with denial deterrence. Reprisal deterrence is the 800-pound gorilla, and denial deterrence is the flea. If our adversaries are thinking twice about using nuclear weapons it's because they're scared of reprisal deterrence. And if they aren't sufficiently scared of reprisal, fractional denial certainly isn't going to stop them. To borrow an analogy used by Thomas Schelling, a Nobel laureate with a deep knowledge of arms control and game theory: Denial deterrence adds to reprisal deterrence like tying an extra cotton string adds to the strength of an aircraft carrier's anchor chain.

Third, even if one agrees with the NPR's argument that missile defense can somehow compensate for the deterrence allegedly lost by reducing the nuclear arsenal, an enormous logical flaw persists: The two alleged "deterrents"--the operational stockpile and missile defenses--are aimed at different countries and aren't interchangeable. Reducing the U.S. operational nuclear stockpile, which is calibrated to Russia's arsenal, isn't going to be compensated by investing in missile defenses to protect against an Iranian attack. Plus, many experts agree that if Iran obtains nuclear weapons, it wouldn't use them in a suicidal first strike. A detailed National Defense University study concluded that Tehran desires nuclear weapons mainly because it feels strategically isolated and that "possession of such weapons would give the regime legitimacy, respectability, and protection." Basically, Iran wants a nuclear capability for deterrence purposes--just like every other nuclear-armed nation. The Polish foreign minister has even admitted that Warsaw is involved with U.S. missile defense plans in Europe to improve diplomatic ties with Washington, not out of any fear of Iranian nuclear attack.

But if Tehran does obtain nuclear weapons, surrounding it with missile defenses, no matter how effective, will never eliminate the threat that a single missile could penetrate the defense system. Thus, the United States can never neutralize the deterrent value of any possible future Iranian nuclear ballistic missiles with any incarnation of missile defense. A nuclear-armed Iran would have to be treated identically by Washington whether or not missile defenses were in play.

The strategic uselessness of missile defenses aimed at intercepting nuclear-tipped missiles is clear (as I have argued before). This is a conceptual problem, not merely a technical one. The reason is simple: There is always a reasonable probability that one or more nuclear missiles will penetrate even the best missile defense system. Since a single nuclear missile hit would cause unacceptable damage to the United States, a missile defense system shouldn't change U.S. strategic calculations with respect to its enemies. Washington should treat North Korea, Iran, and other adversaries the same before and after setting up missile defense systems. Recently, Schelling publicly stated that missile defense will be of dubious value in addressing the possible future threats from Iran.

The danger of overstatement. Exaggerating the abilities of missile defense is downright dangerous and military leaders ought to make sure that it doesn't happen; unfortunately, it does. Take, for example, these claims made in the February 2010 Ballistic Missile Defense Review (BMDR) report: "The United States now possesses a capacity to counter the projected threats from North Korea and Iran for the foreseeable future." And: "The United States is currently protected against the threat of limited ICBM [intercontinental ballistic missile] attack, as a result of investments made over the past decade in a system based on ground-based midcourse defense."

Neither of these statements is remotely true. The current system cannot even reliably intercept a single missile that's launched at a known time and on a known trajectory. None of the various missile defense systems, sea- or land-based, have ever been tested in a realistic setting: For instance, a surprise attack with salvos of missiles with decoy warheads (and other countermeasures) and unknown trajectories. J. Michael Gilmore, the director of the Operational Test and Evaluation Office of the Secretary of Defense, recently testified that "it will take as many as five to seven years to collect" just the necessary data to determine whether the administration's planned missile defense architecture is even sensible. And if future tests do prove it to be an empirical failure will the administration really roll back missile defense? It's unlikely. The long-range plans appear to be unencumbered by any realistic testing requirements.

Unfounded claims of missile defense's effectiveness create a serious risk that political leaders might be misled into mistakenly believing that missile defenses actually work. And if they incorrectly think that missile defense has secured the country by neutralizing the threat of ballistic missile attack, policy makers might be emboldened to stake out riskier and more aggressive regional policies than in the absence of missile defense. A similar mistaken confidence in overwhelming U.S. conventional firepower misled Washington into the Iraq War debacle; nuclear miscalculations would be much more costly.

For this reason, missile defense should not, as the NPR claims it would, play any role in "reassuring allies and partners around the world"; no ally should feel secured by a defensive system that can be penetrated by nuclear-tipped missiles. If allies do feel they have neutralized their adversaries' deterrent forces, they too might be tempted to undertake riskier actions, possibly leading to conflict and ultimately even U.S. nuclear intervention. A misplaced confidence in missile defenses could even lull Washington into complacency regarding the spread of WMD and ballistic missile technology: Imagining that they have largely addressed the threat from ballistic missiles, policy makers might feel less urgency to fight proliferation.

A poor proliferation deterrent. It's often incorrectly asserted that missile defenses dissuade adversaries from researching and producing ballistic missiles. For instance, the BMDR report states: "The United States, with the support of allies and partners, seeks to create an environment in which the acquisition, deployment, and use of ballistic missiles by regional adversaries can be deterred, principally by eliminating their confidence in the effectiveness of such attacks, and thereby devaluing their ballistic missile arsenals."

But the countries developing ballistic missile technology do so for numerous reasons, not just to launch nuclear attacks against the United States. Many countries desire conventional ballistic missile technology for prestige or because of regional considerations. Whether or not a U.S. missile defense system is operational, such nations will still try to acquire ballistic missile technology. In fact, the countries of most interest to the United States--Iran and North Korea--currently have well-developed ballistic missile programs. The BMDR's claims of an already-functioning missile defense shield obviously haven't diminished their ballistic ardor.

Furthermore, space-launch technology and ICBM technology are identical, and U.S. missile defenses are unlikely to dissuade an adversary from pursuing a space-launch capability. So missile defense has been, is, and will be, an empirical failure at dissuading countries of concern to the United States from pursuing ballistic missile programs.

Missile defense spurs proliferation. Instead of dissuading countries from pursuing ballistic missiles, missile defense actually incites proliferation. Adversarial and competitor nations will build up their offensive capabilities to ensure some missiles get through. The development of alternate delivery methods and sneakier attack tactics will be a natural response to the fielding of a U.S. missile defense system.

As the bipartisan Strategic Posture Commission has pointed out, "China may already be increasing the size of its ICBM force in response to its assessment of the U.S. missile defense program." And the BMDR report explicitly states, "Both Russia and China have repeatedly expressed concerns that U.S. missile defenses adversely affect their own strategic capabilities and interests."

As George Lewis and Ted Postol have reported, in the past, Russia had a legitimate concern regarding U.S. missile defense architecture in Eastern Europe. Interceptors based in Poland could "engage essentially all Russian ICBMs launched against the continental United States from Russian sites west of the Urals. It is difficult to see why any well-informed Russian analyst would not find such a potential situation alarming." Similar concerns are now resurfacing.

Considering that missile defense won't change the U.S. strategic equation with respect to Iran or North Korea (except perhaps to engender in leaders a false sense of security), is it really worth unnecessarily antagonizing U.S. relations with Russia and China and possibly sparking Russia's withdrawal from New START?

Just as with nuclear weapons, the U.S. infatuation with missile defense will cause other nations to desire this expensive and destabilizing technology. Following the U.S. lead, both China and India now have missile defense test programs. It doesn't take much imagination to anticipate Pakistan's response. There will be legitimate pressure for Islamabad to attempt to redress this perceived Indian defense by producing more missiles and nuclear weapons. In response, India and subsequently China will likely increase their own stockpiles--in turn increasing pressure on U.S. and Russian strategists to respond. So rather than reducing the value of nuclear weapons, missile defense actually increases it.

Unfortunately, much of the wrongheaded and inaccurate thinking about the deterrent value of missile defense has seeped into the NPR. Thus, there's now an urgent need for an informed, unbiased reappraisal of U.S. strategic thinking on the conceptual basis of nuclear missile defense policy.