Which military alliance was formed as a counter to NATO?

The Warsaw Pact was established in 1955 as a response to the formation of NATO in 1949. This military alliance included the Soviet Union and several Eastern Bloc countries, such as Poland, East Germany, Czechoslovakia, Hungary, Romania, and Bulgaria. The pact aimed to create a collective defense among its members and serve as a means for the Soviet Union to assert its influence over Eastern Europe during the Cold War.

The context of the Cold War is crucial here, as NATO represented Western countries' commitment to mutual defense against potential Soviet expansion. The Warsaw Pact was thus a direct counterbalance, creating a clear division between the Eastern and Western blocs. By aligning these countries under a common military agreement, the Warsaw Pact sought to strengthen the Soviet hold over its satellite states and to deter Western military actions in Europe.

The other options do not represent military alliances that were specifically formed to counter NATO in the same way the Warsaw Pact was. SEATO, for instance, was aimed primarily at Southeast Asia, emphasizing a different geographical focus, while the Alliance of Democratic States and The Coalition of Free Nations do not refer to recognized military alliances established during the Cold War.