What promoted US president Jimmy Carter to withdraw the SALT 2 treaty from senate approval in 1979?

President Jimmy Carter withdrew the SALT II treaty from Senate consideration in 1979 largely due to the Soviet invasion of Afghanistan in December of that year. The invasion heightened tensions between the U.S. and the Soviet Union, leading to concerns over Soviet expansionism. Additionally, the deteriorating geopolitical climate made it politically untenable for Carter to pursue ratification of the treaty, which was seen as a compromise with a now-aggressive adversary. As a result, he decided to abandon the treaty to respond to public and congressional sentiment against the Soviets.