The Soviet war in Afghanistan, also known as the Soviet-Afghan War, was a nine-year conflict involving Soviet forces supporting the Marxist People's Democratic Party of Afghanistan (PDPA) government against the Mujahideen resistance. The latter group found support from a variety of sources including the United States, Saudi Arabia, Pakistan and other Muslim nations in the context of the Cold War. This conflict was concurrent to the 1979 Iranian Revolution and the Iran-Iraq War.

The initial Soviet deployment of the 40th Army in Afghanistan began on August 7, 1978. The final troop withdrawal began on May 15, 1988, and ended on February 15, 1989. Due to the interminable and inconclusive nature of the war, the conflict in Afghanistan has often been referred to as the Soviet equivalent of the United States' Vietnam War.