Does missile defense work?

North Korea’s December 2012 rocket launch and third nuclear test last week has prompted plenty of discussion about the appropriate scope of and funding levels for ballistic missile defense.

In my February (2013) Bulletin of the Atomic Scientists column, I argue that our political and military leaders should be more realistic about what defenses can and can’t do. Here’s how I conclude:

The United States must use the full range of diplomatic, economic, and security tools at its disposal to mitigate the threats posed by North Korea and Iran. Missile defense has a role to play, but it’s neither as grandiose nor as significant as many claim. A sensible approach would condition deployments on realistic assessments of both the actual threat and the effectiveness of our defenses and include more engagement with Russia and China. In fact, overstating the importance and effectiveness of missile defense could provide US policymakers with a false sense of security, which could prompt them to be more aggressive in dealing with rogue states — thereby increasing the risk of war.

Below are some additional thoughts that didn’t make it into the column.

A lot has been written about the virtues of missile defense cooperation with Russia, but there has been a dearth of thinking about what transparency and confidence-building measures could be pursued with Beijing. James Acton put forth some helpful ideas on this front at a recent event on the future of arms control at the Carnegie Endowment for International Peace. James suggests that in return for a more complete picture of US missile defense plans in Asia, Beijing could provide Washington with more information about its conventionally-armed theater ballistic missiles, which are a concern to the United States and its allies.

On the issue of realistically assessing the threat against which missile defenses should be designed, as I’ve noted previously, the main focus should be on the most prevalent threat missiles; namely, the threat posed to US deployed forces and allies by conventionally armed non-strategic range (i.e. short and medium-range) rockets and ballistic missiles. Neither North Korea nor Iran is believed to be capable of striking the US homeland with nuclear-armed missiles, though North Korea appears to be making progress toward such a capability. Focusing on conventionally-armed shorter-range missiles is also likely to be the most effective approach given the technical shortcomings of existing strategic defenses, the fact that, in principle, shorter-range missiles are easier to defend against than longer-range missiles (though any missile that operates outside the atmosphere for a portion of its flight can utilize decoys and countermeasures), and the conceptual shortcomings of defenses against nuclear-armed missiles.  

Well-designed and effective defenses against conventional rockets and ballistic missiles could provide meaningful damage limitation, since the consequences of failing to intercept every conventionally armed missile would of course be less devastating than failing to intercept every nuclear armed missile. That said, it’s important to remember that any defense system can be overwhelmed by a well-equipped adversary capable of fielding sufficient numbers of offensive missiles.

Finally, as North Korea continues to make progress in the development of increasingly longer-range missiles, the pressure to dump more money into the ground based midcourse defense (GMD) system, currently America’s only midcourse national defense system, is likely to increase. But the reality is that existing US strategic defenses are about as effective as they can be at the moment, which is not very effective. More money is unlikely to fix the problems that plague the system faster. In fact, if you believe the National Academy of Sciences, no amount of money is likely to fix the GMD system. If 30 ground based interceptors cant intercept six notional North Korean ICBMs, then its unlikely that more interceptors can. Moreover, as I note in the column, moves to expand the system could undermine relations with Russia, and perhaps more likely, China (since it has a much smaller nuclear arsenal than Moscow) and provide US leaders with a false sense of security.    

The policy implication then, is that at the very least there should be no rush to deploy more long-range defenses until they’re demonstrated to be effective and suitable in successful operational tests. More generally, a fundamental reexamination of the US missile defense program is needed. As Phil Coyle notes in his recent feature story in Arms Control Today:

The basic architectures of the phased adaptive approach and the GMD system are in doubt because so many of the parts do not work, do not exist, or are not achievable for the foreseeable future. Clearly, a major review and reconsideration is required of all elements of both arrangements. In particular, without a scientifically credible path to effective target discrimination, these projects lack the necessary foundation for a successful missile defense system.

Nukes of Hazard
The Center for Arms Control and Non-Proliferation is a Washington,
D.C.-based non-profit, non-partisan research organization dedicated to
enhancing international peace and security in the 21st century.

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