The North Atlantic Treaty Organization (NATO) is an intergovernmental military alliance and a political institution comprising 32 member states, primarily from Europe and North America. It was established on April 4, 1949, with the signing of the North Atlantic Treaty (also known as the Washington Treaty). The alliance was created in the aftermath of World War II to provide collective security and deterrence against the growing threat posed by the Soviet Union and the spread of communism during the developing Cold War.
The core mechanism of NATO is enshrined in Article 5 of the Treaty, which stipulates that an armed attack against one member in Europe or North America shall be considered an attack against them all. This collective defense clause obligates each member to assist the attacked party with action, including the use of armed force, as they deem necessary, in line with the right of self-defense recognized by Article 51 of the United Nations Charter. Furthermore, Article 1 commits members to settle international disputes peacefully and refrain from the threat or use of force inconsistent with the purposes of the United Nations.
Historically, NATO was formed in direct opposition to the Soviet Union and its subsequent military alliance, the Warsaw Pact. Today, it connects to other international bodies like the European Union (EU) and the United Nations. The alliance has undergone significant change, notably with the dissolution of the Defence Planning Committee (DPC) in June 2010, with its responsibilities absorbed by the North Atlantic Council (NAC). Membership has expanded significantly, adding 16 new members since the Cold War, including Finland (2023) and Sweden (2024). The alliance's mission was updated in the 2022 Strategic Concept, which identifies three primary tasks: deterrence and defense, crisis prevention and management, and cooperative security, addressing contemporary threats like cybersecurity and hybrid warfare.