The last remaining nuclear arms control treaty between the United States and Russia will expire on 5 February, marking the end of five decades of legally binding limits on the world’s two largest nuclear arsenals.
US President Donald Trump has yet to respond to a Russian proposal to maintain the treaty’s restrictions, despite warnings from arms control experts that the expiration could trigger an unprecedented nuclear build-up.
The New Strategic Arms Reduction Treaty, known as New START, currently limits each nation to 1,550 deployed strategic nuclear warheads and 700 strategic launchers.
Russian President Vladimir Putin proposed in September 2025 that both countries voluntarily observe these limits for one year after expiration, but the Kremlin has confirmed that Washington has not formally responded to the offer.
Trump dismissed concerns about the treaty’s expiration in January, telling The New York Times: “If it expires, it expires. We’ll just do a better agreement. ”
The US President has suggested any successor agreement should include China, which possesses a significantly smaller but rapidly expanding nuclear arsenal.
Beijing has repeatedly declined participation, arguing that US and Russian stockpiles far exceed its own.
The treaty, which entered into force in February 2011, was extended for five years in 2021—the only extension permitted under its terms.
Russia suspended the treaty’s verification measures in 2023 following Western support for Ukraine, though both nations have continued to observe the numerical limits.
Without the treaty, the United States could deploy an additional 480 nuclear weapons at bomber bases within weeks and load nearly 1,000 more warheads onto submarines within months.
Arms control advocates warn that allowing New START to lapse without replacement would eliminate the final constraint on US and Russian nuclear force levels, potentially spurring China to accelerate its own nuclear expansion.
For the first time since the Cold War’s Strategic Arms Limitation Talks began in 1969, no negotiations are underway or planned to replace the expiring agreement, raising the prospect of a three-way arms race amongst the world’s major nuclear powers.