NATO (North Atlantic Treaty Organization) is a transatlantic defense alliance founded in 1949.
Today, it consists of 31 member countries, of which 14 were part of the former Eastern Bloc. The latest country to join was Finland, which became a member in April 2023.
NATO was created with the aim of preserving peace in the North Atlantic area by deterring armed attacks against members of the alliance.
There are no “supranational” military units within NATO, the national defense forces of the member countries constitute the only military resources.
The core of NATO is Article 5 which reads:
“The parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against all of them and, accordingly, they agree that, in the event of such an armed attack, each of them will /. ../ to assist the attacked party or parties by immediately, individually and in concert with the other parties, taking such measures as it deems necessary, including the use of armed forces, to restore and maintain security in the North Atlantic area.”
Each member state decides on its own defense and security policy, and has veto rights in voting.
Sources: Institute for Foreign Policy, NATO