The Anti-Ballistic Missile (ABM) Treaty was a good idea in its day. Signed in 1972 during a thaw in the Cold War, the treaty's principal goal was to reduce the likelihood of a first strike by either the U.S. or the Soviet Union. Without missile defense, each side understood that launching a first strike against the other's ICBM silos would be disastrous, because the other side would launch a retaliatory strike with its surviving nukes, including submarine-based and bomber-based nukes. But missile defense would create an asymmetry: A reasonably successful first strike might sufficiently weaken the enemy that its reduced arsenal could be handled by a less-than-perfect missile defense. Consequently, with missile defense, each side would be more likely to launch a first strike if it feared the other was considering one. Thus, via a logic that may seem paradoxical, banning a purely defensive option was thought to make each side safer.
President Reagan did not accept this logic, preferring the more straightforward idea that defending the country by shooting down missiles was more peaceful and less morally fraught than by threatening to nuke tens or hundreds of millions of civilians. Thus he launched a research effort known as the Strategic Defense Initiative (SDI) and popularly dubbed "Star Wars."
SDI didn't make it far enough out of the lab during the Reagan or Bush 41 Administration to violate the ABM Treaty, but by the time the Bush 43 Administration came into power, the ABM logic had changed considerably. The Russians were no longer considered the main threat to launch a nuclear missile at the U.S. or its allies. Instead, the main threat came (and comes) from rogue states and non-state terrorist organizations. The latter especially are not subject to the logic of deterrence, and so any missile defense against a potentially nuclear-armed terrorist seems better than none. So thought the Bush Administration when it withdrew from the ABM Treaty in 2002.
Indeed, even before Bush 43 came into office, the U.S. was actively moving in this direction. The National Missile Defense Act of 1999 states: "It is the policy of the United States to deploy as soon as is technologically possible an effective National Missile Defense system capable of defending the territory of the United States against limited ballistic missile attack (whether accidental, unauthorized, or deliberate) . . . ." You can find that policy statement and more at the Missile Defense Agency's website.
The big news in missile defense today was the agreement by NATO to build a missile defense system for Europe, apparently accepting the same post-Cold War logic. Whether Bush and NATO are right that the Cold War logic no longer applies is unclear. Certainly the fact that Russia strenuously objects to European missile defense suggests that the Russians perceive the defense as aimed at Russia, which is itself destabilizing.
But even if Russia could eventually be brought around to accept NATO's benign intent, one objection to missile defense would appear to have survived the Cold War: Missile defense is likely to be porous and costly. Relatively cheap measures, like decoy missiles, can overcome the best currently available technology, and in an arms race between offensive and defensive weapons, the offense would appear to have a great advantage. The best that one could possibly hope for is a very expensive impermeable missile defense that would lead a determined enemy to seek other delivery options.
Does that mean that missile defense remains a bad idea? Not necessarily. A speech last September by NATO Secretary General Jaap de Hoop Scheffer identifies the end of the Cold War and the proliferation of both nuclear technology and missile technology as reasons to go forward with missile defense. But it would be foolish in the extreme to think that missile defense is anything more than a small piece of the security puzzle. Like the Maginot Line to which missile defense has been compared, at best it will slow the enemy down or lead the enemy to take a different route.
Posted by Mike Dorf