New START Treaty

The New Strategic Arms Reduction Treaty (New START) is a bilateral nuclear arms control agreement between the United States and the Russian Federation. It was signed in Prague on 8 April 2010 by Presidents Barack Obama and Dmitry Medvedev, and entered into force on 5 February 2011 after ratification by the US Senate and Russia's Federal Assembly. The treaty replaced the 1991 START I agreement, which had expired in December 2009, and superseded the 2002 Strategic Offensive Reductions Treaty (SORT, or "Moscow Treaty").

New START sets three central numerical limits on each party's deployed strategic nuclear forces, to be reached within seven years of entry into force:

• 1,550 deployed strategic nuclear warheads;
• 700 deployed intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and heavy bombers equipped for nuclear armaments;
• 800 deployed and non-deployed ICBM launchers, SLBM launchers, and heavy bombers.

The treaty also established a verification regime including on-site inspections, data exchanges, notifications about strategic forces, and a Bilateral Consultative Commission to address implementation issues. It does not cover non-strategic ("tactical") nuclear weapons, nor does it constrain missile defence or conventional strategic systems, points that have remained politically contested.

Originally set to expire on 5 February 2021, New START was extended for five years (until 5 February 2026) shortly after President Joe Biden took office, in an exchange of notes with Moscow in early 2021. In February 2023, President Vladimir Putin announced that Russia was suspending its participation, halting on-site inspections and the regular meetings of the Bilateral Consultative Commission, though Moscow stated it would continue to observe the central numerical limits. The US State Department has since reported that Russia is no longer providing the treaty's notifications and data exchanges, leaving the future of formal US–Russia strategic arms control uncertain.