Time is running out: the nuclear arms reduction deal between the United States and Russia, New START, is set to expire at the end of Wednesday. World leaders, including Pope Leo XIV, have publicly called for the agreement’s extension or preservation.
START stands for Strategic Arms Reduction Treaty. The most recent bilateral deal was signed by Barack Obama and Dmitry Medvedev in 2010 and is the last remaining treaty on nuclear reduction between the two countries. Earlier arrangements date back to the Strategic Arms Limitation Talks (SALT-I) of 1972.
New START caps deployed strategic nuclear warheads at 1,550 each and limits deployed strategic delivery vehicles and systems — heavy bombers, intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) — to 800 each. It also includes provisions for mutual inspections and data exchanges to verify compliance.
Earlier START agreements include START I, initiated during the Cold War and entering into force in 1994, and START II, agreed in 1993 but never entering into force amid rising tensions. New START was intended as a renewed framework for arms reduction. Originally set to last ten years and expire in February 2021, it was extended by five years through an agreement between US President Joe Biden and Russian President Vladimir Putin, bringing the current deadline to 2026.
What happens if New START expires? Once the treaty lapses, the two largest nuclear powers would no longer be bound by numerical limits for their strategic arsenals. Kremlin spokesperson Dmitry Peskov warned, “This is very bad for global security.” Without the treaty’s transparency and inspection mechanisms, analysts say the world could face a renewed, unchecked nuclear arms race and greater uncertainty that undermines predictability and crisis stability.
In September 2025, Putin offered that Russia would unilaterally adhere to the deal for an additional year to allow time for renegotiation; then-US President Donald Trump called the proposal “sounds like a good idea,” but stayed non-committal. By January 2026, Trump told the New York Times, “if it expires, it expires,” adding he expected “we’ll just do a better agreement.” Trump has argued that China — which has rapidly expanded its nuclear arsenal — should be included in any new arrangement.
Relations since Russia’s full-scale invasion of Ukraine in 2022 have strained US-Russia ties but initially did not terminate New START. Half a year into the war, Russia barred US inspections at strategic sites, and in 2023 Moscow announced it was suspending participation in New START, citing US support for Ukraine. Despite this, Russia has reportedly continued to respect the treaty’s numerical limits.
START history also connects to Ukraine: START I-era provisions led Ukraine to transfer Soviet-era nuclear warheads to Russia in exchange for security assurances from Russia, the US and the UK under the Budapest Memorandum — assurances that have since been a focus of controversy.
China’s role complicates any new treaty. Beijing is estimated to possess about 600 nuclear warheads and has rejected calls to cap its arsenal, saying it remains relatively small compared with US and Russian stockpiles. Washington’s push to include China in a future agreement makes a straightforward extension of New START less likely.
Technical and strategic changes also challenge the treaty’s scope. Russia has developed and deployed nuclear-capable systems not covered by New START, including hypersonic missiles and the Poseidon nuclear-capable underwater drone. Meanwhile, proposals such as Trump’s planned space-based missile defense system, the “Golden Dome,” have been criticized as undermining the mutual vulnerability that underpins deterrence. Russian officials have warned that deployment of missile defenses on Greenland, for example, would provoke military responses.
Europe is watching closely. The treaty’s possible expiry has raised concerns about the reliability of the US nuclear umbrella and prompted debate about European nuclear arrangements. Some have suggested that France and the UK could extend protection to other European states; German Chancellor Friedrich Merz has confirmed discussions are taking place, though he said “the time is not right yet.” Key questions remain, including command-and-control and decision-making over nuclear use. Russia has argued any new treaty should include British and French arsenals as well.
Former signatories have urged action. Barack Obama called on the US Congress to preserve New START, warning expiry would “pointlessly wipe out decades of diplomacy and could trigger a new arms race that would make the world less safe.” Dmitry Medvedev, deputy chairman of Russia’s National Security Council, said the end of the treaty should “alarm everyone” and that lacking alternatives would accelerate the “Doomsday Clock.”
Even with offers of unilateral adherence and diplomatic calls for extension, differences over China, new weapons systems, missile defense and mutual trust make a straightforward salvage of New START or its successor uncertain. Its expiration would mark a significant shift in the post–Cold War arms control architecture and raise fresh risks for global security.
This article was translated from German.