The North Atlantic Treaty Organization (NATO), also called the North Atlantic Alliance, is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defense in response to an attack by any external party. NATO's headquarters are in Brussels, Belgium, one of the 22 member states across North America and Europe, the newest of which, Albania and Croatia, joined in 2009.
Central America (1953)
Federal Republic of Germany (1955)