Answer:
Communism wasn't contained inside the Soviet Union. It had to be spread worldwide to achieve utopia. Some countries had adopted communism to help realize that goal, including: Warsaw Pact Nations: Albania, Bulgaria, Czechoslovakia, Romania, Poland and Hungary (communist from about 1945 to 1991). The Warsaw Pact was a military treaty signed by these countries and Russia. In short, it guaranteed that they would come to each other's aid if targeted by another country.