North Atlantic Treaty Organization
Overview
The North Atlantic Treaty Organization is a military alliance of 32 member countries from Europe and North America. NATO was established in 1949 by 12 founding nations, and its primary purpose is to provide a collective security framework—originally designed to defend Western European nations against aggression from the Soviet Union.
The organization is founded on collective defense, meaning that an attack on one member is treated as an attack on all. Since the fall of the Soviet Union, NATO has broadened its membership and scope—covering around 10 million square miles and almost a billion people.
The 2022 Russian invasion of Ukraine—which is not a NATO member but shares borders with three alliance nations—revived Cold War-era tensions between an enlarged West and an aggressive Russia. Finland (2023) and Sweden (2024) both joined NATO in light of Russia's move.
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