Today the world may have reached a defining geopolitical moment similar to the late 1940s, when the East-West alignment that characterized the cold war emerged from the chaos of World War II.
As that war shattered old alliances and created new ones, so a US invasion of Iraq appears likely to scramble an order that has seemed as fixed as the stars for almost 60 years. Poland - remember that old term, East bloc? - is sending troops to the Middle East, but not France. Bulgaria is one of America's new good friends, while Germany, for the moment, has been downgraded from "ally" to "acquaintance."
The nascent US-Russian relationship has cooled, while China looks on warily, unsure what all this means for Asia. The Middle East? It will be different. How different, and in what manner, few who have had much experience in that battered region are willing to guess.
"I think we're actually in a new period without much modern historical analogy," says Jim Walsh, an international security expert at Harvard University's John F. Kennedy School of Government in Cambridge, Mass. "A lot depends on what happens in Iraq."
In the wake of the defeat of Nazi Germany, countries did not stay divided along the lines of victor vs.
vanquished, as they mostly did following World War I. Instead, they reorganized themselves, like iron filings lined up by two magnets, along the poles of newly perceived threats.
To the West, it was the rise of an expansionist Soviet Union that drove its organizing principle. While it did take some years for enmity to fade, both Germany and Japan lined up with their conquerors by the end of President Harry Truman's time in office. In the East, the Soviets and their satellites responded in kind.
Similarly, today's reorganization is driven by a new threat, and the world's differing perceptions of its importance. In his speech Monday night, President Bush made clear that the desire to prevent further terrorist attacks on the US is a main reason for his push to topple Saddam Hussein - whether there are explicit links between Iraq and Al Qaeda or not.
Whether it takes one year or five years, eventually Saddam would foment an attack on the American mainland, claimed Mr. Bush.
France and Germany and many other European nations simply do not see Iraq posing such an apocalyptic threat. This differing perception is helping drive the old NATO allies apart - along with such other items as resentment about American unilateralism and insensitivity. "The problems of international security have changed dramatically, and there is a gap in the perception of what needs to be done on the part of [the US] and Europe," says Robert Pfaltzgraff, an expert in international security at Tufts University's Fletcher School of Law and Diplomacy in Somerville, Mass.
Inevitably this means alliances will be reshuffled, says Mr. Pfaltzgraff. NATO will still exist, but it will be different, as it grows larger with the admission of new members of the old Soviet East bloc - nations that happen to feel allegiance to the US for helping them gain their freedom.
It's likely that some US troops and military equipment will move their permanent homes from Germany to new jumping-off points further east, though such a change will necessarily take some time.
This rejigging of the Western alliance can work both ways, of course. It's easy for Americans to forget that France was wary of German entry into NATO in the first place, and that for a century prior it's foreign policy was driven largely by its fear of a German invasion.
Yet today they are pushed together by mutual belief that the US is making a blustery mistake. "The remarkable thing about France today is that it feels so comfortable with the Germans," says Pfaltzgraff.
Meanwhile, Russia, the core nation of the West's former common adversary, has taken an opportunity to stick it to Washington on a major security issue. Whether that means the developing rapprochement with the US is now over is another matter. Long term, President Vladimir Putin still appears committed to at least decent relations with Washington, says John Ruggie, a former assistant secretary general of the UN, who is now teaching at Harvard.
Through cleverness or happenstance, the Russians allowed France to take the lead in saying it would block the US move to war in the Security Council. "The Russians essentially allowed the French to go out and hang themselves," says Mr. Ruggie.
Of course, the most profound ramifications of a US invasion of Iraq might occur in the Middle East itself. The administration claims that Iraq will become a stable, pro-US platform, exporting both oil and democracy. Critics see something else - a breakup of something that is a nation in name only, and is in fact a stitched-together quilt of warring tribes.
At the very least, the US will find itself, postwar, in the midst of a very unstable neighborhood. American soldiers and civil personnel will be conquerors in the heart of the Arab world, with Iran on one side, and Syria on the other. "They will be eyeball to eyeball across fluid and sometimes hot borders," says Akbar Ahmed, chair of Islamic studies at American University.