NATO’s “open door policy” is based upon Article 10 of the Washington Treaty, which states that membership is open to any “European State in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area”.
The enlargement of the Alliance is an ongoing and dynamic process. Since the Alliance was created in 1949, its membership has grown from the 12 founding members to today’s 28 members through six rounds of enlargement in 1952, 1955, 1982, 1999, 2004 and 2009.
The first three rounds of enlargement – which brought in Greece and Turkey (1952), West Germany (1955) and Spain (1982) – took place during the Cold War, when strategic considerations were at the forefront of decision-making.
The fall of the Berlin Wall in November 1989, signalled the end of the Cold War and was followed by the dissolution of the Warsaw Pact and the break up of the Soviet Union, ending the division of Europe. The reunification of Germany in October 1990 brought the territory of the former East Germany into the Alliance. The new democracies of Central and Eastern Europe were eager to guarantee their freedom by becoming integrated into Euro-Atlantic institutions.
NATO enlargement was the subject of lively debate in the early 1990s. Many political analysts were unsure of the benefits that enlargement would bring. Some were concerned about the possible impact on Alliance cohesion and solidarity, as well as on relations with other states, notably Russia. It is in this context that the Alliance carried out a Study on NATO Enlargement in 1995 (see above).
Post-Cold War enlargement
Based on the findings of the Study on Enlargement, The Alliance invited the Czech Republic, Hungary and Poland to begin accession talks at the Alliance’s Madrid Summit in 1997. These three countries became the first former members of the Warsaw Pact to join NATO in 1999.
At the 1999 Washington Summit, the Membership Action Plan was launched to help other aspirant countries prepare for possible membership.
Bulgaria, Estonia, Latvia, Lithuania, Romania and Slovakia and Slovenia were invited to begin accession talks at the Alliance’s Prague Summit in 2002 and joined NATO in 2004. All seven countries had participated in the MAP.
Bucharest Summit decisions
At the Bucharest Summit in April 2008, Allied leaders took a number of steps related to the future enlargement of the Alliance.
Several decisions concerned countries in the Western Balkans. The Allies see the closer integration of Western Balkan countries into Euro-Atlantic institutions as essential to ensuring long-term self-sustaining stability in this region, where NATO has been heavily engaged in peace-support operations since the mid 1990s.
- Albania and Croatia were invited to start accession talks to join the Alliance and joined NATO in April 2009.
- The former Yugoslav Republic of Macedonia* was assured that it will also be invited to join the Alliance as soon as a solution to the issue of the country’s name has been reached with Greece.
- Bosnia and Herzegovina and Montenegro were invited to start Intensified Dialogues on their membership aspirations and related reforms. Montenegro was invited to join MAP in December 2009 and Bosnia and Herzegovina in April 2010.
Allied leaders also agreed at Bucharest that Georgia and Ukraine, which were already engaged in Intensified Dialogues with NATO, will one day become members. In December 2008, Allied foreign ministers decided to enhance opportunities for assisting the two countries in efforts to meet membership requirements by making use of the framework of the existing NATO-Ukraine Commission and NATO-Georgia Commission – without prejudice to further decisions which may be taken about their applications to join the MAP.
|4 April 1949
||Signature of the North Atlantic Treaty by 12 founding members: Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States. Article 10 of the treaty provides basis NATO’s “open door policy”.
|18 February 1952
||Accession of Greece and Turkey.
|6 May 1955
||Accession of the Federal Republic of Germany.
|30 May 1982
||Spain joins the Alliance (and the integrated military structure in 1998).
||With the reunification of Germany, the new German Länder in the East become part of NATO.
||At the Brussels Summit, Allied leaders reaffirm that NATO remains open to the membership of other European countries.
|28 September 1995
||Publication of NATO Study on Enlargement.
|8-9 July 1997
||At the Madrid Summit, three Partner countries – the Czech Republic, Hungary and Poland – are invited to start accession talks.
|12 March 1999
||Accession of the Czech Republic, Hungary and Poland, bringing the Alliance to 19 members.
|23-25 April 1999
||Launch of the Membership Action Plan (MAP) at the Washington Summit. (Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia join the MAP.)
|14 May 2002
||NATO foreign ministers officially announce the participation of Croatia in the MAP at their meeting in Reykjavik, Iceland.
||President Leonid Kuchma announces Ukraine’s goal of eventual NATO membership.
|21-22 November 2002
||At the Prague Summit, seven Partner countries – Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia – are invited to start accession talks.
|26 March 2003
||Signing ceremony of the Accession Protocols of the seven invitees.
|29 March 2004
||Accession of Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia.
|21 April 2005
||Launch of the Intensified Dialogue on Ukraine’s aspirations to NATO membership and related reforms, at an informal meeting of foreign ministers in Vilnius, Lithuania.
|21 September 2006
||NATO foreign ministers in New York announce the decision to offer an Intensified Dialogue to Georgia.
|28-29 November 2006
||At the Riga Summit, Allied leaders state that invitations will be extended to MAP countries that fulfil certain conditions.
|2-4 April 2008
||At the Bucharest Summit, Allied leaders invite Albania and Croatia to start accession talks; assure the former Yugoslav Republic of Macedonia¹ that it will be invited once a solution to the issue of the country’s name has been reached with Greece; invite Bosnia and Herzegovina and Montenegro to start Intensified Dialogues; and agree that Georgia and Ukraine will become members in future.
|9 July 2008
||Accession protocols for Albania and Croatia are signed.
|1 April 2009
||Accession of Albania and Croatia.
|4 December 2009
||NATO foreign ministers invite Montenegro to join the Membership Action Plan.
|22 April 2010
||NATO foreign ministers invite Bosnia and Herzegovina to join Membership Action Plan, authorizing the North Atlantic Council to accept the country’s first Annual National Programme only when the immovable property issue has been resolved.