In September 1995, they released a “Study on NATO Enlargement”, which explained why enlargement was appropriate and how it should be approached. It also set out a road map that countries seeking membership could follow.

The Allies saw the enlargement of the Alliance as a means of supporting NATO’s broader goal of enhancing security and extending stability throughout the Euro-Atlantic area. It would underpin the process of democratisation and the establishment of market economic systems in candidate countries. They emphasised that enlargement would threaten no one, because NATO would remain a defensive Alliance whose fundamental purpose was to preserve peace and provide security to its members. With regard to the “how” of enlargement, the Allies established a framework of principles to follow. New members would assume all the rights and responsibilities of current members, and would have to accept the policies and procedures in effect at the time of their entry; no country should enter with the goal of closing the door behind it, using its position as a member to block the accession of other candidates; countries should resolve ethnic disputes or external territorial disputes before joining NATO; candidates should be able to contribute to the missions of the Alliance; and no country outside the Alliance would have the right to interfere with the process.

During 1996-97, NATO officials conducted intensified dialogues with 12 countries which had expressed an active interest in NATO membership. The candidacies of all countries were thoroughly examined from a wide range of perspectives.

At the end of this process, the NATO leaders, meeting in Madrid in July 1997, agreed that three countries – the Czech Republic, Hungary and Poland – were at that point ready to move towards membership. The terms of membership were negotiated and, in the course of 1998, the proposed enlargement was approved through the legislative processes of all current NATO members and the three candidate states. By the time of the Washington Summit in April 1999, all three countries had become fully-fledged NATO members.

One of the highlights of the April 1999 Washington Summit was thus the presence, for the first time, of the Heads of State and Government of the Czech Republic, Hungary and Poland. They formally joined the Alliance on 12 March 1999, bringing the number of member countries to 19. A number of measures were successfully completed by each of the new members prior to accession, in order to ensure the effectiveness of their future participation in the Alliance.