When did the Soviet Union invade Afghanistan?

The Soviet Union invaded Afghanistan on December 24, 1979, beginning the Soviet-Afghan War. What ensued was close to a decade of combat as the Soviets sought to prop up a weak communist government against Islamist fighters called the Mujahideen. The Russians were swift in their invasion, overthrowing and executing poor President Hafizullah Amin and appointing Babrak Karmal as president, but they found unexpected resistance before finally leaving in 1989.