Final answer:
The Soviet Union's intervention in Eastern Europe was aimed at preserving and spreading communism to create a protective buffer zone against the West. NATO was formed in response to protect Western interests. The Soviet Union's control over Eastern Europe also involved economic and resource advantages for its own recovery post-World War II.
Step-by-step explanation:
The Soviet Union intervened in Eastern European countries in the 1950s and 1960s primarily for the preservation of communism. After World War II, the USSR aimed to establish a buffer of friendly governments as protection against potential aggression from the West. As the Cold War intensified, the Soviet Union supported communist parties in Eastern European countries, leading to the establishment of communist governments that mirrored the Soviet system. The economic aid and military support provided to these satellite states were often at the expense of their own resources, and while some in these war-torn countries hoped for stability and growth, they faced the reality of Soviet control.
The creation of NATO was a direct response to this expansion, aiming to protect Western countries from Soviet aggression. The intervention in Eastern European countries was not out of humanitarian assistance, promotion of democracy, or military occupation for its own sake, but rather to keep these countries within the communist sphere of influence and to prevent the spread of Western capitalism and democracy.