The Soviet invasion of neighboring Afghanistan in December 1979 sparked a bloody nine-year conflict with the Mujahedeen until Soviet forces withdrew in 1988-89, dooming the communist Afghanistan government to defeat by Afghan popular resistance backed by the USA and other powers. The Soviet invasion had enormous implications on the global stage; it prompted the US Senate to refuse to ratify the hard-won SALT II arms-limitation treaty, and the USA and 64 other countries boycotted the 1980 Moscow Summer Olympics. For Afghanistan, the invasion served to prolong the interminable civil war that pitted central government against the regions and faction against faction. The country remains locked in conflict over 30 years later, with no end in sight. For over a year before the invasion the communist Afghan government, installed following a coup and intent on forcibly modernizing the country's civil law in the face of centuries of feudal practices, had called for Soviet armed assistance in its efforts to overcome the open rebellion of the Mujahedeen. Fearing the international consequences should the Afghan government be toppled, the Soviets decided to invade. From the outset, though, they failed to understand that communist principles were incompatible with traditional tribal relationships - especially in a country notorious for its poor communications and resistance to centralization.