What are the reasons for the formation of a bipolar system of international relations?

Striving for peace and security in the world served as an impetus for the development of 2-pole relations.
The founding of the NATO bloc in 1949, oriented against the states of the socialist camp.

Also, the signing of the Warsaw Pact in May 1955 in response to the FRG’s entry into NATO.

The motivation for the nuclear arms race was world domination and superiority over other countries.
The deterrent factor that prompted the negotiations was the threat of nuclear war and the destruction of humanity.