What would happen after the New START treaty ended 

The New START treaty is a nuclear arms reduction treaty between the United States and Russia that was signed on April 8 2010, but on February 5, 2026, the treaty expired, due to the Trump administration not responding to Russia's proposal to replace it, leaving the question of what would happen next.

While the New START treaty had many rules for both the United States and Russia the main thing about the treaty was that it put a limit on the number of weapons that could be made or deployed between the United States and Russia. The treaty states that less than 700 intercontinental ballistic missiles, submarines launched ballistic missiles and heavy bombers equipped for nuclear armaments could be deployed at once. Less than 1,550 nuclear warheads on deployed intercontinental ballistic missiles, submarines launched ballistic missiles and heavy bombers equipped for nuclear armaments and less than 800 deployed and non-deployed intercontinental launchers, submarine launched ballistic missiles and heavy bombers equipped for nuclear armaments, with the New START treaty ended this could lift the restrictions that were putted in place.

With the New START treaty ended this could lead to a new problem since both the United States and Russia hold 90 percent of the world nuclear arsenal which could have led to a big problem since with the treaty ended this could lead to the United States or Russia to increase their nuclear arsenal.