In the context of the enlargement of NATO, Article 10 of the North Atlantic Treaty is the origin for the April 1999 statement of a "NATO open door policy".[1][2] The open door policy requires a consensus in favour of countries applying to join NATO, as all member states must ratify the protocol enabling a new country to become a member of NATO. The open door policy "is aimed at promoting stability and cooperation".[3]

History

Post-Cold War enlargement of NATO

George W. Bush's March 2004 speech (mentions open door policy at 7:03)

Following the Eastern European Revolutions of 1989, countries from the former Eastern Bloc expressed their interest in joining NATO. During a March 1992 visit to Warsaw, NATO secretary general Manfred Wörner said that the "doors to NATO are open".[4] During the December 1994 OSSE conference in Budapest, the United States and its NATO allies stated that no European countries should be prevented from joining the alliance.[5]

According to Vladimir Putin, he had asked whether or not Russia could join NATO in 1999. He recounted in February 2024 that Bill Clinton answered him, "I’ve talked to my team. No, no, it’s not possible now."[6]

On 12 March 1999, Poland, Hungary, and the Czech Republic joined NATO as the first former Eastern Bloc states, beginning the enlargement of NATO eastwards.[7] When Estonia, Latvia, Lithuania, Bulgaria, Romania, Slovakia, and Slovenia joined on 29 March 2004,[8] US president George W. Bush prepared for even further enlargement of the alliance. During the welcoming ceremony held the same day, he said:

The April 2008 Bucharest Summit communiqué re-affirmed the NATO allies' "commitment to keeping NATO's door open to any European democracy willing and able to assume the responsibilities and obligations of membership, in accordance with Article 10 of the Washington Treaty."[10] At that summit, Ukraine was invited to join the Alliance.[11]

In a 5 December 2015 "Statement by NATO Foreign Ministers on Open Door Policy" Montenegro was invited to join the alliance, and the signatories encouraged "Georgia to continue making full use of all the opportunities for coming closer to the Alliance." They remained "committed to the Open Door Policy, a founding principle of the Washington Treaty" and encouraged "partners to continue to implement the necessary reforms and decisions to prepare for membership," while they would "continue to offer political and practical support to the efforts" of the partners.[12]

At the end of November 2020, it became known that the NATO Summit in 2021 would consider a return to the open door policy, including the issue of providing Georgia with a Membership Action Plan (MAP).[13]

On 9 February 2021, the prime minister of Ukraine, Denys Shmyhal, stated that he hoped that Ukraine would be able to receive an action plan for NATO membership at the same time as Georgia.[14] In response, the NATO Secretary-General confirmed during Shmyhal's visit to Brussels that Ukraine is a candidate for NATO membership.[15]

On 14 June 2021, a communiqué issued at 2021 Brussels summit reaffirmed commitment to the open door policy, as well as "all elements" of the decision made at the 2008 Bucharest Summit that Georgia and Ukraine will become members of NATO.[16]