Key Points:

The tides of history seldom leave a high watermark as stark as that left on the eastern shore of the Black Sea this week. Here ends the illusion of a single superpower.

Georgia, a balmy little country in the Caucasus Mountains, has been a staunch friend of the United States since its release from the Soviet Union, supportive in the Middle East, provider of the only non-Russian channel of oil and gas from Central Asia to Europe.

Hardly anyone outside the Kremlin turned a hair this year when Georgia applied for membership of Nato, as did Ukraine. The Western alliance has been steadily admitting Eastern European countries since the Soviet collapse and there seemed no reason to stop at the borders of the former USSR.

In April, President Bush assured Ukraine that Russia's opposition would not be allowed to veto its ambitions or those of Georgia.

At the Nato summit a few days later those surrender monkeys, France and Germany, quailed at giving Ukraine and Georgia a date for entry but all agreed it was a matter of, "not if but when".

How the world can change in a week.

In the middle of last week Georgia's smart young president, Mikheil Saakashvili, a New-York-trained lawyer who speaks perfect English, felt sufficiently confident of his country's Western credentials to break a ceasefire agreed with rebels in a largely Russian region that would like to secede, South Ossetia.

By the middle of this week Russia's troops were touring Georgia in trucks, merrily teasing foreign correspondents trying to guess whether they would take the capital or rest content with having driven Georgians from South Ossetia and bombed the country and moved into strategic centres at will.

It was the Russian Army's first foray abroad since Afghanistan 1979 and there was not a thing anyone could do about it.

Bush accused the Russians of seeking "regime change" in Georgia and warned them they were acting without world support. Last week, before attending the Olympics, he had something to say to China about illegal detentions and the rule of law.

You've got to hand it to this lamest of all ducks, he is shameless to the end.

From somewhere in the depths of Washington, Richard Cheney said Russian aggression must not go unanswered, and it sounded like the last grumble of thunder before the sun returns.

US diplomacy was back to its best, flying in humanitarian relief on military aircraft, backing French mediation and making a virtue of the inevitable: Russia's withdrawal from a Georgia now minus South Ossetia and probably its other renegade region, Abkhazia.

Meanwhile, Ukraine, the Baltic republics and others on or near Russia's borders _ especially Poland where Nato has been planning to base missiles over Moscow's objections _ have a new geopolitical picture to consider.

Through it all, I kept recalling the imperial declarations from the White House, circa 2002.

Enraged by events the previous year, America's national security statements coldly observed that it had emerged from the Cold War with more military force than any other power, or combination of powers, that could be brought against it.

And it was henceforth to be a matter of primary importance to America's security that no rival power, or combination of powers, would be able to threaten US interests anywhere in the world.

America would reserve the right to act at any time, in any place, in any manner of its choosing to suppress a perceived threat before it could harm Americans. It would prefer to act with international support, but was fully prepared to act alone if necessary.

A decade earlier a better President Bush had known the limits of military power. Hailing a "new world order" after the collapse of the Soviet bloc, Bush Snr had recognised that unrivalled power carried the seeds of its own destruction.

When Iraq seized Kuwait, he provided the leadership that was not coming quickly enough from the United Nations. He, too, might have moved unilaterally if need be, because the cause was clear and right, limited and achievable. He rescued Kuwait and withdrew, recognising Iraq was a sovereign state to be handled by international sanctions and diplomacy. His son's presidency must have been a private nightmare.

The next President should be able to restore some credibility in Washington. Barack Obama took a restrained, even-handed view of events in Georgia this week, and John McCain, after an attempt to sound tougher, recognised it was not a place for a military response.

Power is a subtle commodity, driven as much by national need and pride as military capability. Post-communist Russia possesses as much pride and nuclear power as it had in the Cold War. It has been remarkably quiescent as former allies have gone west.

Now it is back in the balance and, properly handled, its weight can be welcomed.