The motivation behind the Soviet's invasion of Afghanistan is an issue that continues to be studied and debated.  There are various theories as
to why the invasion occurred.

• in order to support the stability of the Marxist regime that was under attack from Muslim rebels
• to act as the final stop in establishing a long term Russian goal to reach the Indian Ocean and to free herself from the bonds of being a "superpower in a landlocked state"
• to secure Soviet southern flanks in the wake of U.S. attempts to disrupt? weaken? its southern Muslim Republics
• to protect/secure/ensure their range of influence in the region and to elevate her communist regime against the attack of Afghan Mujahideens (Muslim rebels, literally meaning "strugglers") and Pakistani based Afghan Tanzeems (militant groups)
• it was a result of the continuing efforts by Soviet Premier Leonid Brezhnev, members of the Soviet Defense Military, and the Organization of Communist International
• the pro-Moscow government that was put in place after the April 1978 coup was not able to combat Muslim uprising that had previously swept through Iran, and would come to spread to the millions of Muslims in the Soviet Union

  Soviet Premier Leonid Brezhnev