As the United States erects a missile-defense system in Central Europe, Russian politicians have begun to protest that this location represents an attack on them. They sometimes hint that it may be sufficiently threatening to derail the current talks aimed at negotiating a new strategic arms-limitation treaty. At least up to the present, the U.S. answer has been that missile defense is directed against the developing Iranian threat to Europe. The argument is that no ally is likely to support the United States in a crisis if its own country is held hostage by Iranian missiles.