North Atlantic Treaty Organization. NATO is an organization to which many European countries and the US and Canada belong. They agree to give each other military help if necessary. Culture NATO was originally formed by 12 countries in 1949 to defend Europe and North America against what was seen as the threat of Soviet attack after the Second World War. They agreed that an armed attack against one or more of them should be considered an attack against them all, and set up military bases all over Europe to protect themselves against the Communists. After the end of the Cold War in the late 1980s, and the joining of East and West Germany in 1990, it was suggested that NATO should become a political organization rather than a military one. In 1995 NATO started a major new approach called Partnership for Peace, to make political and military links stronger between NATO and the central and eastern European countries. Its members are now Albania, Belgium, Britain, Bulgaria, Canada, Croatia, the Czech Republic, Denmark, Estonia, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Turkey and the US. Nato's main offices are in Brussels.