Washington: The last remaining nuclear arms control treaty between the United States and Russia has expired, ending more than five decades of formal limits on the world’s two largest nuclear arsenals.

The New Start treaty, which ended on February 5, had capped each side at 1,550 deployed strategic nuclear warheads and allowed inspections to verify compliance. With the treaty now over, there are no longer any legally binding limits on the nuclear forces of the two countries.

The agreement was signed in 2010 and extended once in 2021. Talks on a new treaty never moved forward, mainly because of rising tensions over the war in Ukraine and wider political disputes.

Russian President Vladimir Putin had earlier proposed keeping the current limits in place for one year without a formal treaty. Moscow says it is still waiting for a clear response from the United States. U.S. officials have not accepted the proposal, saying any future deal should be broader and could include China.

The Kremlin says Russia does not want a new arms race but is ready to live in a world without nuclear limits if necessary. U.S. officials have also said they will protect national security but have not announced any immediate increase in nuclear weapons.

President Donald Trump has spoken about the need for new negotiations and has suggested that future talks should not be limited to Russia alone. He has also made remarks about nuclear testing in the past, which raised concerns among arms control experts, though no testing plans have been confirmed.

With the treaty gone, inspection visits and data sharing between the two countries have stopped. Experts warn this could lead to more mistrust and uncertainty, as neither side will have a clear picture of the other’s nuclear forces.

International groups and former leaders have urged Washington and Moscow to return to the negotiating table to avoid a new nuclear arms race. They say the end of the treaty increases the risk of misunderstanding and makes the world less safe.

For now, both countries say they are open to talks. But with no agreement in place, the era of strict nuclear limits between the United States and Russia has come to an end.