12/03/2010 - 05:49

Re-examining the conceptual basis of strategic missile defense

Yousaf Butt

Yousaf Butt

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


Discussions of the technical flaws of strategic missile defense are nearly as old as the idea itself. Considerably less attention, however, has been paid to examining whether such a system -- even if technically feasible -- should be a desirable goal. The plan to move forward with a NATO-wide missile defense system demands we now take a closer look at whether the conceptual basis of strategic missile defense is sensible.

Technical issues. Back in 1968, Richard Garwin and Hans Bethe published a detailed technical critique of the then-proposed limited missile defense system designed to protect the continental United States against Chinese nuclear missiles. That system would have relied on nuclear-tipped interceptor missiles; the hit-to-kill technology that is currently used was unavailable then. As that seminal paper articulated: "[O]ffensive tactics and cheap penetration aids could nullify the effectiveness of this system and any other visualized so far." Decades later, this fundamental insight remains true. These "penetration aids" (known more broadly as "countermeasures") remain one of the biggest technical challenges for all strategic missile defense systems currently under consideration by the US government. For instance, both the Navy's Standard Missile 3 (SM-3) and the Ground-Based Missile Defense (GMD) can be defeated with simple decoy warheads and other cheap countermeasures.

Unfortunately, a number of high-level government policy documents, e.g. the latest US Nuclear Posture Review (NPR) and the Ballistic Missile Defense Review (BMDR), are rife with logical and factual errors that perpetuate the illusion that missile defense will offer protection from an adversary's nuclear deterrent. For instance, the BMDR asserts that "[t]he United States is currently protected against the threat of limited ICBM attack, as a result of investments made over the past decade in a system based on ground-based midcourse defense." Such statements are patently untrue. The current system cannot even reliably intercept a single missile that is 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. GMD has had a particularly bad test record, having regularly failed, even in highly scripted tests, and even when defense contractors were holding military operators' hands.

In response to these inherent technical flaws with both proposed midcourse missile defense systems (SM-3 and GMD), Professors George Lewis and Theodore Postol have recently suggested a drone-based boost-phase missile defense system as a technically feasible alternative. Such a system would be based upon stealthy drones that could shoot down ballistic missiles in powered flight shortly after they have been launched from fixed known sites in countries of concern, e.g. Iran and North Korea. As the authors state, this system "requires no new technologies or science to be effective, reliable, robust, and intimidating against the adversaries of concern."

Conceptual issues. Although Lewis and Postol are correct that their proposed boost-phase system is a technically superior alternative to the midcourse systems under consideration, the implications of creating a truly workable missile defense system should be examined more closely to see if it would increase or decrease US and NATO security.

The thinking is that if missile defense could be made "good enough" -- for argument's sake, say more than 70 percent effective -- then this will be a net plus for US (or NATO) security since it would discourage our adversaries from aiming nuclear-tipped ICBMs at us. In fact, the official goal of missile defense is well articulated in the BMDR document: "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 even if the drone missile defense system -- or any other -- could be made to work, it 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, may encourage the nation to develop a ship-launched nuclear cruise missile instead. Since a cruise missile is more difficult to detect and attribute to a given country, our adversaries would be less inhibited in using it as compared to an easily detected ICBM, which has a clear point of origin; thus, if a "functional" missile defense were to encourage our adversaries to exchange even a single ICBM for a ship-launched cruise missile or a ship- or submarine-borne one, this would decrease our security. Of course, they may opt to develop these alternate delivery methods in any case, but creating a functional strategic missile defense will certainly force them in this dangerous direction.

Since the network of US Defense Support Program (DSP) satellites can pinpoint the origin of any ICBM, it is the least stealthy delivery method of nuclear weapons. An ICBM launch is the easiest of all delivery methods to ascribe to a given nation. This feature of ICBMs poses an enormous obstacle to their use and is precisely why mutual assured destruction (MAD), a fear-based doctrine that both sides could annihilate the other, worked during the Cold War. All other delivery methods have a less evident origin and therefore nations would be less inhibited in using them -- if only marginally.

Compared to other nuclear weapons delivery platforms, an additional benefit of ICBMs is that they are wholly domestic, allowing for tighter command and control -- this is not the case, for example, with a ship-borne device that would be delivered and activated by a team. Individuals in such a team, which would include the ship's crew, could possibly steal or misappropriate the device en route; further, the ship could be seized by a third country or non-state actors.

Thus, if our adversaries cannot be discouraged from possessing nuclear weapons, it makes little sense to attempt to change their delivery method from easily traceable ICBMs to stealthier methods, which our adversaries would be less deterred from actually using. In short, so long as our adversaries possess (or aspire to possess) nuclear weapons, we should not aim to discourage their mounting them on ICBMs -- in fact, we should aim to discourage all other delivery methods besides ICBMs.

In light of this conceptual flaw in strategic missile defense, the US and NATO aspiration to a functional system should be critically re-examined. The real danger of strategic missile defense is that it may work to discourage ICBMs -- without discouraging the nuclear weapons themselves.