The Berlin Blockade highlighted the military vulnerability of Western Europe and the need for a formal security alliance.

In 1949, the United States, Canada, and ten Western European nations signed the North Atlantic Treaty, creating NATO.

NATO (North Atlantic Treaty Organization) is a collective security alliance.

Its cornerstone is Article 5, which states that an armed attack against one member shall be considered an attack against them all.

The formation of NATO represented a major departure from the traditional U.S. policy of avoiding peacetime military alliances.

The Soviet Union viewed NATO as an aggressive alliance aimed against it.

In response to West Germany's entry into NATO in 1955, the Soviet Union and its Eastern European satellite states formed their own military alliance.

This alliance was known as the Warsaw Pact.

The formation of these two opposing military blocs solidified the division of Europe into East and West.

The military standoff between NATO and the Warsaw Pact became the central feature of the Cold War in Europe.