In December 1979, the Soviet Union sent troops into Afghanistan and established military and political control over much of the country. The Soviets wanted to end the Afghan civil war and develop a friendly socialist government on its border.
The invasion was a turning point in the Cold War. It was the only time the Soviet Union invaded a country outside the Eastern Bloc. Soviet leaders hoped that a rapid and complete military takeover would exemplify the Brezhnev Doctrine, which stated that once a country became socialist Moscow would never permit it to return to the capitalist camp.
The United States and its European allies sharply criticized the Soviet move into Afghanistan.
US President Carter had closely watched the buildup to the invasion. The administration’s reaction showed that it had clung to the hope that the Soviets would not invade. Carter wrote a sharply-worded letter to Brezhnev denouncing Soviet aggression. The President announced his own doctrine to protect Middle Eastern oil supplies from falling under Soviet power. The US administration also enacted economic sanctions and trade embargoes against the Soviet Union. The United States also provided aid to the Afghan insurgents.
These actions were Washington’s attempt to end the Soviet operations in Afghanistan. Instead, Soviet troops remained there for ten years. Millions of lives were lost and billions of dollars spent. When the Soviets did withdraw, they left a shattered country. The Taliban, an Islamic fundamentalist group, seized control. Osama bin Laden used Afghanistan as a training base from which to launch terrorist operations worldwide.
Source: The Soviet Invasion of Afghanistan and the U.S. Response, 1978–1980
US Department of State, Public domain