After an initial period of uncertainty, the newly free democracies of eastern Europe began asking for admission to Nato in 1993-94. Nato leaders did not initially want the Alliance to enlarge, and many senior figures, especially those with Cold War experience, still do not want it to do so. But Tuesday's announcement confirms it is going to happen. As one senior Nato official put it, it was something on which the Alliance was "doomed to agree".
The road to enlargement began with the fall of the Berlin Wall in 1989, and the "two plus four" negotiations between the two Germanys and the four occupying powers - the United States, the then Soviet Union, Britain and France - which led to the reunification of Germany in October 1990. The Warsaw Pact began to break up, a dissolution completed in 1991; the Soviet Union followed in the same year.
Since the beginning of the decade, Nato has had to deal with two big problems in parallel: its own restructuring to reflect a change in the "threats" and risks of a new world order; and how to make enlargement acceptable to those eastern European states which did not want to or could not join Nato, especially Russia and Ukraine.The absorption of eastern Germany, reunified with the West into Nato, was the first step in the Alliance's eastward enlargement. Many people - including senior Russian officials - have since claimed that assurances were given that after subsuming eastern Germany, Nato would expand eastward no further. Nato officials have always denied that. The two plus-four talks, they say, were all about Nato's presence in eastern Germany after reunification.
That may have been true at the time, but it may also have given the Russians the impression Nato had given an undertaking not to enlarge further. It was not until 1993 that the newly free democracies of eastern Europe started clamouring for admission to Nato.
Meanwhile, the Nato London summit of July 1990 began the shift towards a new Nato role, though that process is still incomplete. The summit agreed changes to nuclear strategy until then frozen in the Cold War mould - and "extended the hand of friendship" to Russia, resulting in the creation of the North Atlantic Co-operation Council as a forum for co-operation between Nato - the 16 - and Russia - "plus one".
At the Rome summit the following year, Nato initiated a "new strategic concept", though it differed little from the old one and Nato has only just agreed to revise its strategic orientation to reflect the new world order.
Russia had huge problems with the idea of Nato enlarging. Its senior generals and internationally-minded politicians could see the advantages of a new and friendly relationship with the West. But as Russia's economy continued to crumble, they had to maintain face in front of a domestic audience which had been brought up to see Nato as Napoleon, Hitler, the Teutonic Knights and the grandsons of Genghis Khan (all of whom had invaded Russia) rolled into one.
The door to Nato had to be left open for a second wave of new members, and other agreements had to be made with the states which were unlikely ever to join.
At the Brussels summit in 1994, Nato began the Partnership for Peace programme, which now embraces virtually all Nato and east European states, including Russia.
The final approach to enlargement began with the Berlin summit in June 1996.
The geopolitical and strategic questions of enlargement could not be divorced from the domestic politics of the main players. In the US, powerful constituencies in the mid-West were of Polish or Czech ancestry - and the US was in an election year.
For domestic reasons, Moscow displayed anger in public, acceptance in private. In the end, Russia realised it had no choice but to accept Nato enlargement - it just had to sell it to its own people.
On 27 May, Nato and Russia signed the Founding Act on Mutual Relations, Co-operation and Security.
The long road to enlargement is not over: all 16 Nato nations have to ratify the accession of the first three new members to be invited. When they join, in April 1999, the invitations to the next wave will probably be issued.
What matters now is whether the military forces of states which were opponents until 1991 canwork together efficiently.Reuse content