The U.S. built Stinger ground-to-air anti-aircraft missile, supplied to the Afghan Mujahedeen in very large numbers, struck a decisive blow to the Soviet war effort as it allowed the lightly-armed Afghans to effectively defend against Soviet helicopter attacks. This effort to support the Afghan Mujahedeen in resisting Soviet oppression led successfully to the first major military defeat of the Soviets. The forced retreat of the Red Army in Afghanistan proved an important contributing factor in the eventual collapse of the Soviet Empire.