New START Treaty

The New Strategic Arms Reduction Treaty (New START) was signed by the United States and Russia in 2010 and entered into force in February 2011, capping each country's deployed strategic nuclear warheads and delivery vehicles (intercontinental ballistic missiles, submarine-launched ballistic missiles and heavy bombers) at agreed levels, and establishing an intrusive verification regime of on-site inspections and regular data exchange between the two parties. It succeeded the original START treaty of 1991 and represented the last operative element of the bilateral US-Russia strategic arms-control architecture built up since the 1970s. The treaty's own Article XIV permitted the parties to agree a single extension of up to five years beyond its original ten-year term. That extension was exercised in February 2021, fixing the treaty's terminal date at 5 February 2026 as a matter of treaty law rather than of subsequent political choice, since no further extension was legally available under the treaty's own terms. No successor agreement was negotiated before that date, and New START accordingly expired on 5 February 2026. The expiry is significant because it means that, for the first time since the original Strategic Arms Limitation Talks (SALT I) agreement of 1972, there is no negotiated numerical limit on the strategic nuclear arsenals of the United States and Russia, and no bilateral verification or on-site inspection regime between them. This sits alongside the collapse of the broader European arms-control architecture, including the termination of the Intermediate-Range Nuclear Forces (INF) Treaty in 2019, the abandonment of the Open Skies Treaty by both principal parties, and the effective defunctness of the Conventional Armed Forces in Europe (CFE) Treaty, together removing the mechanisms that had allowed states to plan against known rather than worst-case adversary capabilities.

• 1 New START: US-Russia treaty signed 2010, in force February 2011, capping deployed strategic warheads and delivery vehicles with mutual verification.
• 2 Succeeded the original START treaty of 1991; the last operative element of bilateral US-Russia strategic arms control.
• 3 Article XIV permitted only one extension of up to five years; exercised in February 2021, fixing the terminal date at 5 February 2026.
• 4 Expired 5 February 2026 with no successor negotiated.
• 5 First time since SALT I (1972) with no negotiated limit on US-Russia strategic nuclear arsenals and no bilateral verification regime.
• 6 Sits alongside the collapse of Europe's broader arms-control architecture: INF Treaty terminated (2019), Open Skies abandoned, CFE Treaty effectively defunct.
• 7 Absence of verification forces states to plan against worst-case rather than known adversary capabilities, a classic driver of the security dilemma.

New START's expiry on 5 February 2026, following its one permitted extension in 2021, was cited as leaving the United States and Russia without any negotiated limit on strategic nuclear arsenals for the first time since 1972.