Answer: formation of Warsaw pact was a part of a process of bi-polarization (in ideological, political and military term as well) of the world. Already during Marshall plan (rejected by Eastern European countries) "Iron curtain" started to divide European continent. In 1949 NATO was established. Warsaw pact of reaction to NATO and also reaction to the integration of Western Germany into NATO. Warsaw pact came into existence in 1955.
Explanation: Warsaw Pact was established between Russia and seven eastern European countries in 1955. At that time there was already a Cold War between two blocks. The pact was established as a balance of power.