New START

What it is

New START (formally the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms) was the bilateral agreement between the United States and Russia that set the strictest quantitative limits on strategic nuclear arsenals since the original 1991 START I. The treaty capped each side at 1,550 deployed strategic warheads, 700 deployed delivery vehicles (intercontinental ballistic missiles, submarine-launched ballistic missiles, and nuclear-capable heavy bombers), and 800 total deployed and non-deployed launchers and bombers. Its verification mechanism, 18 annual on-site inspections combined with continuous National Technical Means monitoring, allowed inspectors to count actual warheads loaded onto missiles during short-notice visits at ICBM bases, submarine bases, and air bases. That inspection architecture, more than the numerical ceilings, is what analysts consistently identify as the treaty's core contribution: it gave both governments verified transparency into each other's deployments.

History

The agreement replaced START I, which had been in force from December 1994 until its expiry in December 2009, and superseded the 2002 Strategic Offensive Reductions Treaty (SORT or Moscow Treaty), which lacked any verification provisions. US President Barack Obama and Russian President Dmitry Medvedev signed the treaty on April 8, 2010, in Prague. The US Senate ratified it 71 to 26 in December 2010, and it entered into force on February 5, 2011. New START secured one extension: on February 3, 2021, both governments agreed to add the maximum five years permitted under the treaty text, setting a firm expiry of February 5, 2026. Russia's February 2022 invasion of Ukraine ended the cooperative climate. On February 21, 2023, Moscow announced it was suspending its implementation, halting participation in inspections and biannual data exchanges. Washington declared Russia in material breach and inspections never resumed. Russia proposed in September 2025 that both sides voluntarily observe the central limits for one additional year, but the US government did not formally respond.

Current state

The treaty lapsed on February 5, 2026, with no successor in place and no inspections conducted since early 2023. The lapse ended roughly 50 years of continuous US-Russia bilateral arms control. Both governments have said informally they will not immediately exceed the warhead caps, and early 2026 US assessments found no large-scale Russian warhead upload. But neither side is legally bound. Russia retains an estimated reserve of several hundred non-deployed warheads that could be uploaded onto existing delivery systems, a process that takes anywhere from hours for bombers to years for ICBMs. The path to a successor is blocked: the US insists any new agreement must include China, and Beijing has rejected that demand as unrealistic, citing an approximate 8-to-1 disparity in warhead numbers between China and each of the two larger powers.

Relationships

New START was the last pillar of a bilateral arms-control architecture that stretched back to the 1972 SALT I agreement. The INF Treaty, which banned ground-launched missiles in the 500 to 5,500 km range, had already collapsed in 2019 when the US withdrew after citing Russian violations. With New START gone, no legally binding numerical ceiling constrains either the US or Russian arsenal, the first such gap since the early Cold War era. SIPRI estimated roughly 12,187 total global nuclear warheads as of January 2026, with the US and Russia holding around 90 percent between them. The loss of the inspection regime is considered by most arms-control analysts to be the more consequential near-term damage, because it eliminates the shared data infrastructure that gave both sides confidence in reading each other's deployments and dampened the action-reaction spiral.

What to watch

Whether the US or Russia begin uploading warheads beyond the previous caps, particularly at bomber bases where the process can be completed in hours. Whether the Trump administration drops its China-inclusion condition to restart bilateral US-Russia talks. China's arsenal trajectory toward a US Pentagon-projected 1,000 warheads by 2030, the figure Washington cites in arguing any successor framework must be trilateral. Any European-led multilateral initiative, which SIPRI has flagged as a potential mechanism for filling the verification gap in the absence of the bilateral framework.