Britannica Sources used in this answer

Why did START II seek to eliminate MIRVs from intercontinental ballistic missiles?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Strategic Arms Reduction Talks U.S. Pres. Barack Obama talking with Russian Pres. Dmitry Medvedev, just before the two leaders issued a joint statement about their continued cooperation on the New START Treaty, December 4, 2009.

The START II treaty sought to eliminate multiple independently targetable reentry vehicles (MIRVs) on intercontinental ballistic missiles (ICBMs) primarily to reduce the strategic instability associated with these weapons.

During the Cold War, the combination of large, accurate missile forces and MIRV technology created concerns regarding a "window of vulnerability." Because a single MIRVed missile could carry multiple warheads capable of striking widely separated targets, critics argued that a relatively small portion of an adversary's force could theoretically destroy a large number of the other side's land-based ICBMs in a preemptive strike. By eliminating MIRVs, the treaty aimed to remove these controversial, high-capacity delivery systems—such as the U.S. Peacekeeper missile and the Russian SS-18—thereby decreasing the incentive for either side to launch a preemptive attack and enhancing overall strategic stability.123