The North Atlantic Treaty Organization (NATO) was created on 4 April 1949. It was Canada’s first peacetime military alliance. It placed the country in a defensive security arrangement with the United States, Britain, and Western Europe. (The other nine founding nations were France, Norway, Denmark, Belgium, Netherlands, Luxembourg, Portugal, and Italy.)

During the Cold War, NATO forces provided a frontline deterrence against the Soviet Union and its satellite states. More recently, the organization has pursued global peace and security while asserting its members’ strategic interests in the campaign against Islamic terrorism. As of 2021, there were 30 member countries in NATO.