Final answer:
The anti-West alliance headed by the Soviets was called the Warsaw Pact, formed in response to NATO in 1955 and consisted of the Soviet Union and Eastern European communist nations.
Step-by-step explanation:
The anti-West alliance headed by the Soviets was called the Warsaw Pact. Formed in 1955 as a response to the formation of the North Atlantic Treaty Organization (NATO), the Warsaw Pact was a military alliance between the Soviet Union and various Communist nations of Eastern Europe, which included Albania, Bulgaria, Czechoslovakia, Hungary, Poland, Romania, and East Germany, among others.
It was constructed as a collective defense against what the Soviet Union perceived as a threat from Western Europe and in particular a resurgent West Germany.
NATO and the Warsaw Pact effectively divided Europe into two opposing blocs during the Cold War: the capitalist democratic nations of the Western Bloc aligned against the communist nations of the Eastern Bloc. The existence of these alliances exemplified the geopolitical divisions of the time and set the stage for various proxy wars and the broader strategic competition between the United States and the Soviet Union.