The New Strategic Arms Reduction Treaty lapsed on 5 February 2026, removing the last bilateral pact restricting American and Russian nuclear forces. Signed in Prague in April 2010 by Barack Obama and Dmitry Medvedev, it took effect on 5 February 2011 and succeeded START I (1991, expired December 2009). It capped each side at 1,550 deployed strategic warheads, nearly 30% below the 2002 ceiling. Originally due to end in 2021, it was extended once by five years. For the first time since 1972, no legally binding cap now applies to the strategic nuclear weapons of the two powers.