The correct answer is: "expansion of the Soviet Union’s influence around the world.".
After WWII, The US had adopted the containment strategy, a foreign affairs approach which focused on stopping the spread of communism worldwide. A related policy was, for example the Marshall Plan, a US initiative that sent funds for rebuilding Western Europe under the influence of the US. The intention was to influence that the Western European powers would side with the US and act as a barrier for containing communism, that was in fact suceeding on the Eastern regions of the continent.