The Soviet Union sent troops to Afghanistan in 1979 because it wanted to come to the aid of its ally, the Parcham faction, which was more moderate in its outlook toward moving the country towards communism. The Parcham faction had signed a treaty of Friendship and Cooperation with the U.S.S.R. the previous year. The United States began to fund the mujadeen resistance, who were opposed to both the Afghan government and the Soviet occupation. These same mujadeen would later form the ideological corps of the people who masterminded the attack on the World Trade Center in 2001.

Between 600,000 and 2 million Afghanis were killed during the war, which lasted until 1989. Of the 600,000 Soviet troops who served in Afghanistan, 14,453 lost their lives and more than 469,000 became sick or were wounded. More than five million Afghanis were displaced and fled to Pakistan. Another two million Afghanis were displaced within their own country, seeking shelter from the violence of the war and the factional fighting that ensued.