On April 4, 1949, foreign ministers from 12 nations signed the North Atlantic Treaty in the blue-and-gold splendor of the US Departmental Auditorium on Constitution Avenue in Washington. The goatskin-clad text promised mutual defense against armed attack. The Marine Band program for the occasion included - inappropriately, some thought - the songs "It Ain't Necessarily So" and "I Got Plenty Of Nothin'."
Thus NATO, the North Atlantic Treaty Organization, was born. Arguments began immediately. Who was going to pay for this thing? What kind of strategy would it have? Should new members be allowed in? Where would armed forces come from?
Fifty years on, the arguments continue. As dignitaries return to Washington for this week's celebration of NATO's 50th anniversary, critics are raising hard questions about the alliance's purpose in today's post-cold-war world. The Kosovo crisis could yet split allies apart.
But it may be worth remembering that NATO has had hard times before. And somehow, something that began as a hollow shell did not turn out too badly.
"The Alliance faced challenges and met them, however imperfectly," writes National Defense University Prof. Richard Kugler in a recent NATO history. "Its ... actions and strength in times of turmoil are a key reason the West won the Cold War. If the past is prologue, it can rise to the occasion again."
One thing NATO has not been is particularly fast-moving. Its 1949 creation was fully two years after the beginning of the long stand-off with the Soviet Union.
Its initial geopolitical goals, to paraphrase its founding secretary-general, Lord Ismay, were to keep the Americans in, the Germans down, and the Russians out. Each of these goals, in turn, handed NATO leaders challenges that were precursors of the problems of today.
In the years immediately after World War II, it was not clear the Americans would stay in - would remain engaged in Europe. At NATO's founding, Truman administration officials promised Congress the move would not lead to permanent stationing of US troops on European soil.
Then the Korean War, which raised fears of communist expansion, and the explosion of the Soviet Union's first atomic weapon changed the equation. President Truman raised the military budget and sent five Army divisions to Europe. NATO formed an integrated command, and a long accretion of armed forces began.
Keeping the Germans down - making sure they remained a committed European partner - has similarly not always seemed foreordained. It was not until 1955, 10 years after the fall of Hitler, that the alliance felt comfortable enough to allow West Germany in.
Keeping the Soviets out was the alliance's core purpose. Yet that took the will to pursue a 40-year arms race. One of the most difficult military steps the alliance ever undertook occurred in the 1980s, when European allies agreed to accept intermediate-range US nuclear missiles, over often heated domestic opposition. The move was needed, leaders felt, to counter a Soviet midrange nuclear threat.
Few critics argue that NATO was unneeded in the past. The cold war ended with hardly a shot fired, after all. The difficult issue now is what comes next, when the Washington NATO party is over?
"Is it a birthday celebration or a funeral?" says Andrew Pierre, a fellow at the US Institute of Peace and author of a new report on NATO at 50.
The question of new members remains a problem. Before the eruption of fighting in Kosovo, the 50th anniversary festivities were to include discussion of whether Slovenia or other aspirants are ready to be invited to join the NATO club.
Expansion is sure to be an agenda item, and new members Hungary, Poland, and the Czech Republic will be officially welcomed as full partners. But momentum toward a second round of expansion appears to be slowing, worry advocates.
Not everyone thinks that is a bad thing. Critics argue that the bigger NATO gets, the more its original focus is lost, and the harder it is to make decisions. The current Kosovo crisis - where 19 nations get to weigh in - may be a case in point.
Kosovo is also an uncomfortable reminder that NATO has yet to fully define its role in the post-cold-war world. Alliances are typically allied against something. Without the Soviet Union as an adversary, what is NATO doing here, anyway?
Fighting instability, say its proponents. "The need remains for there to be a guardian force in the heart of Europe," says Robert Ellsworth, former US ambassador to NATO.
Fighting ghosts, say critics. They insist the US attempt to get the alliance to commit to operating in the Middle East simply shows how outmoded the old structure is in the face of nuclear proliferation, terrorism, and other modern threats.
"There seems to be little inclination on the part of NATO partisans to confront the main issue: Is the alliance really relevant to post-cold-war Europe," says Ted Galen Carpenter of the Cato Institute.