Which group was NATO formed in response to?

NATO, or the North Atlantic Treaty Organization, was established in 1949 primarily in response to the perceived threat posed by the Soviet Union and the spread of communism during the early years of the Cold War. The founding members of NATO sought to create a collective defense mechanism that would ensure mutual protection in the event of an attack from the Soviet Union or its allies. The North Atlantic Treaty, signed in Washington, D.C., laid the groundwork for military collaboration among its member countries, emphasizing that an attack against one is considered an attack against all, thereby deterring potential aggression.

The focus on the Soviet Union reflects the geopolitical landscape of the time, where tensions between Western democratic nations and the Eastern bloc were significantly heightened. This context led to the establishment of NATO as a counterbalance to Soviet military expansion and influence in Europe.

In contrast, other organizations like the United Nations, European Union, and League of Nations were established for different purposes, such as promoting international cooperation and peacekeeping. They do not serve as direct military alliances in the way NATO does, nor were they specifically formed in response to the threat posed by the Soviet Union.