Which one of the following is not a US led alliance.

Warsaw Pact

The correct answer is option (1) - Warsaw Pact

In response to the formation of NATO, the Eastern Bloc, led by the Soviet Union, formed its own military alliance known as the Warsaw Pact in 1955, which included countries from Central and Eastern Europe. It was led by the Soviet Union. Its principal function was to counter NATO’s forces in Europe. The Warsaw Pact, a military alliance among Eastern Bloc communist countries, formally became inactive on July 1, 1991. The dissolution of the Warsaw Pact occurred as a result of the political changes and the end of the Cold War in Europe, which led to the disintegration of the Eastern Bloc and the eventual collapse of the Soviet Union.