The last nuclear disarmament treaty between the US and Russia expired on Thursday, raising concerns over nuclear proliferation and potential arms race.
The so-called "New START" nuclear arms reduction treaty, signed between Moscow and Washington in 2010, limited the number of deployed strategic nuclear warheads for both countries. Last night, at 01:00 CET, this treaty expired.
"The expiry of the New Start treaty marks a grave moment for international peace and security," UN Secretary-General Antonio Guterres announced, urging both countries and Russia to quickly agree on a new framework.
"This dissolution of decades of achievements could not come at a worse time - the risk of nuclear weapons being used is at its highest level in decades," he warned in a statement.
The International Campaign to Abolish Nuclear Weapons (ICAN) criticised both the US and Russia, urging them to publicly commit to respecting the treaty’s limits while negotiating a replacement.
The New START treaty put a cap of 800 launchers and heavy bombers, as well as 1,550 deployed strategic warheads, with provisions for verification on both countries.
The treaty’s expiration comes amid suspended inspections since 2023, following Russia's large-scale military invasion of Ukraine in 2022.
In September 2025, Vladimir Putin proposed to extend the terms of the treaty by one year - a proposal that the US President Donald Trump had described as a "good idea," but which theUS did not follow up on.
