Minimum deterrence and missile defenses: U.S. and Russia going forward

Ratification and entry into force of the New START agreement open the door for possible additional reductions in both states' numbers of deployed long-range nuclear weapons and launchers, but the matrix of post-New START agreement involves nonlinearities with respect to the relationship between minimum deterrence and missile defenses. NATO's Lisbon summit in 2010 invited Russia to participate in a European missile defense system, but Russia is wary of any theaterwide antimissile system that could grow into a more ambitious deterrent-denial force pointed at Russia. Minimum deterrence would drop the numbers of U.S. and Russian strategic nuclear weapons to 1,000 or fewer, but getting Moscow and Washington to move well below 1,000 would require parallel reductions and/or restraints on the part of other nuclear weapons states and a missile defense regime of "cooperative security" rather than mutual suspicion.