The vote was 80 to 19, 12 more votes than the two-thirds majority required. A succession of amendments that would have set conditions for future Nato expansion and US financial obligations were all rejected. When the final vote was taken it was decided that senators would call out their votes from their assigned seats, rather than from anywhere in the chamber, a ceremonial adopted for votes regarded as of historical significance.
Mr Clinton described the bill's passage as a "milestone on the road to an undivided, democratic and peaceful Europe", and he reaffirmed US commitment both to Nato and to continued US involvement in Europe.
"The message this vote sends is clear," he said, "American support for Nato is firm; our leadership for security on both sides of the Atlantic is strong and there is a solid bipartisan foundation for an active US role in the world."
Mr Clinton had earlier described Nato expansion as progress in "realising the dream of a generation - a Europe that is united, democratic and secure for the first time since the rise of the nation states on the European continent".
The US Secretary of State, Madeleine Albright, who is the daughter of Czech immigrants to the US, welcomed the Senate vote as "a moment of injustice undone, of promises kept, and of a unified Europe begun".
The White House had watched the debate with concern since it opened more than a month ago, worried not that the inclusion of the Czech Republic, Hungary and Poland would be rejected, but that the Senate might impose a three-year moratorium on further expansion, or restrict US subsidies on weapons sales to the new members.
At the outset there were also complaints from opponents of Nato expansion that the debate was being nudged into odd corners of the Senate timetable to keep it out of the limelight. In the past week, however, the debate was scheduled in continuous sessions, and produced one of the liveliest and spirited Senate debates in years.
Proponents of Nato expansion had argued from the perspective of US obligations to the victims of the Cold War, the vision of a united Europe, and the benefits to US defence companies. Opponents spanned a broad spectrum of opinion, from prominent Russian specialists and left-wing idealists such as Ben Cohen, of Ben & Jerry's ice-cream, who feared Russian pique and the rise of Russian nationalism, to right-wing American isolationists who saw no reason for American engagement in Europe now that the Cold War was over.
The vote, however, which makes the US the fifth country to ratify Nato expansion, suggested that the extent of opposition, at least in Congress, had been exaggerated.Reuse content