This thesis claims that there are other factors, apart from the Soviet aggression, which are equally important in clarifying the Soviet invasion of Afghanistan. Despite the fact that the idea that the Soviet Union would be pleased to see a client regime in her neighbors is embraced, more arguments are needed to be discussed to explain such a large scale invasion. Soviet Union and Afghanistan had developed sincere affairs since 1950s when the Soviet investments began to reach a substantial level. Well then, how this good relation deteriorated and finally resulted in an armed struggle? In fact, the Soviet efforts to build a socialist regime in Afghanistan bore fruit in 1978; nevertheless only in one year, the USSR invaded a country which put a red star in its banner and never posed a threat to the Soviet lands. Kremlin might have considered Afghanistan was a piece of cake comparing to its former military actions but the results were beyond the Soviet expectations.