At first they were only 12, now they are 31. NATO member states meet for a summit in Vilnius, Lithuania, to discuss in particular defense financing or Ukraine’s membership. Founded in 1949, NATO gradually expanded to include the countries of Eastern Europe after the end of the Cold War.

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Twelve founding members in 1949

At the end of World War II, on April 4, 1949, the foreign ministers of twelve Western countries met in Washington to sign the North Atlantic Treaty: Belgium, Canada, Denmark, the United States, France, Iceland, Italy, Luxembourg, Norway, the Netherlands, Portugal and the United Kingdom. The text creates a political and military alliance between the signatories in the context of the Cold War. The North Atlantic Treaty Organization (NATO) was born.

Four new states by 1991

Three years later, in 1952, a first expansion was decided. To strengthen its presence in south-eastern Europe, NATO welcomed Greece and Turkey. West Germany, which was at the center of tensions with the Eastern bloc, officially joined the alliance in 1955. Then it was necessary to wait until 1982 for the integration of a new state, Spain.

East expansions after the fall of the Wall

The end of the Cold War paved the way for expansion towards the former Eastern Bloc countries. Hungary, Poland and the Czech Republic joined the alliance in 1999, before a new wave of members joined in 2004: Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia. After Slovenia, NATO is gradually integrating several other Balkan countries, all of which have followed the “Membership Action Plan” drawn up in 1999. Albania and Croatia joined in 2009, Montenegro in 2017 and North Macedonia in 2020.

Bosnia and Herzegovina is working on a membership action plan. In addition to the case of Ukraine, which was the focus of discussions at the Vilnius summit, another former Soviet republic, Georgia, has started talks to join NATO.

Finland, last to come… before Sweden?

Finland and Sweden are already involved in NATO-led operations and have long maintained their desire for “non-alignment”. Russian aggression in Ukraine has shifted borders: just under three months after the start of the war, in May 2022, the two countries applied for membership. Finland will officially become a member of the alliance in April 2023. After Turkey blocked its candidacy, Sweden appears to be the next signatory state, with Ankara giving the green light on Monday 10 July.