US Military aid was sent to the Afgan rebels to oppose the Soviets invasion - that's was the official version.  In actuality covert US military aid was sent BEFORE the Soviet invasion.  A million Afgans died for little reason except to torment the Soviets.  End result - 911 and the phony Iraqi War.

Taken from Wikipedia- Soviet-Afgan War

Like many other anti-communist movements at that time, the rebels quickly garnered support from the United States. As stated by the former director of the CIA and current Secretary of Defense, Robert Gates, in his memoirs From the Shadows, the American intelligence services began to aid the rebel factions in Afghanistan 6 months before the Soviet deployment. On July 3, 1979, US President Jimmy Carter signed an executive order authorizing the CIA to conduct covert propaganda operations against the communist regime.

Carter advisor Zbigniew Brzezinski stated "According to the official version of history, CIA aid to the Mujahadeen began during 1980, that is to say, after the Soviet army invaded Afghanistan, 24 Dec 1979. But the reality, secretly guarded until now, is completely otherwise." Brzezinski himself played a fundamental role in crafting U.S. policy, which, unbeknownst even to the Mujahideen, was part of a larger strategy "to induce a Soviet military intervention." In a 1998 interview with Le Nouvel Observateur, Brzezinski recalled:

We didn't push the Russians to intervene, but we knowingly increased the probability that they would...That secret operation was an excellent idea. It had the effect of drawing the Soviets into the Afghan trap...The day that the Soviets officially crossed the border, I wrote to President Carter. We now have the opportunity of giving to the Soviet Union its Vietnam War.^[20]