The North Atlantic Treaty Organization (NATO) is a military alliance of 31 member countries from North America and Europe. Founded in 1949, NATO’s primary purpose is to ensure the security and defense of its members through collective defense, as enshrined in Article 5 of the NATO treaty.

NATO’s collective defense principle means that an attack on one member is considered an attack on all, which has been a cornerstone of the alliance’s strategy since its creation. Over the years, NATO has expanded its membership and adapted to new security challenges, including counterterrorism, cyber threats, and crisis management, while promoting democracy, stability, and peace across the globe.