The idea that a pre-emptive strike could save the world a heap of trouble isn't entirely idle. Think, if Genghis Khan could have been taken out when he was still the leader of just a band and not the whole Mongol race, Europe and Asia would have been saved several million dead and the destruction of much of its civilisation. Remove Napoleon from the scene on his return from his ill-fated Egyptian foray and Europe would have been a different place.

The last century doesn't provide such good examples, of course. To have "changed regime" in Berlin in the early Thirties would have meant overturning a democratically elected leader in Hitler. As for the efforts by the allies to stop the course of the Russian revolution with troops after 1918, the results were disastrous despite having well-armed local allies.

Nonetheless George Bush has done something in the last week to set out the parameters to pre-emptive action. "We owe it," he put it in Maine last weekend, "to the future of civilisation not to allow the world's worst leaders to develop and deploy and therefore blackmail free countries with the world's worst weapons." And he went on to define such enemies of the people as regimes intent on building up weapons of mass destruction, oblivious of international law and UN resolutions, governments who imprisoned their opponents without trial and who could not claim democratic legitimacy at home.

Significantly, nowhere in the series of speeches he made this week did Mr Bush actually name these rogue regimes. But it is pretty clear reading the descriptions whom he must have meant. The government which is spending by far the most on weapons of mass destruction, and is now planning to raise its budget by an increase greater than the total defence spending of Europe, is, of course, based in Washington. Not only is it building an arsenal the like of which the world has never seen, it has unilaterally withdrawn from the treaties designed to limit the spread of nuclear weapons, and has refused to accept any kind of international monitoring of its chemical or nuclear weapons facilities.

It has a government in power without the legitimacy of a democratic majority, in the hands of a coterie from a single part of the country and clearly aiming at a dynasty of rule. Its rhetoric is one of violent aggression against anyone seen as its enemies. It opponents are locked up without trial or the right to habeas corpus.

Of course there are those who say the country's threats are greatly exaggerated and the rhetoric of world mastery must not be confused with a real intention of using its weaponry in defiance of international law. True, it has a has a history of interfering with and invading its neighbours ? Panama, Grenada, Haiti et al. But since the long and debilitating war in Vietnam, it has kept largely to its own region.

Of course it has a peculiarly obnoxious regime, ready to poison its own people with corrupt capitalism and deregulated pollution. But give it time, and pressure from the outside world, and it will pay up its UN dues, rejoin the nuclear proliferation pacts and the Kyoto treaty and start behaving as a responsible member of the community again.

Against this, the hard men of the right would say that time is exactly what the world does not have on its side. Washington has showed itself determined to enforce its hegemony, come what may. It has shown itself ready to use weapons of aerial bombardment that make no discrimination between combatants and civilians, to show precious little remorse when it is guilty of "mistakes".

It is no friend of democracy, having announced its refusal to deal with the only two elected leaders of the Islamic world ? Khatami in Iran and Yasser Arafat in Palestine, the latter the only Arab leader ever elected with western observers checking the process. The country has armed and succoured state terrorism and assassination by the Israelis. It has installed the worst sort of warlord gangsters in Afghanistan and, according to "intelligence", been party to upsetting (albeit briefly) the elected president of Venezuela. The world cannot afford to await its next move.

The problem remains the practicalities. Whereas in Afghanistan the allies could rely on a local opposition force on the ground, no such scenario can be relied on in this case. The Spanish speaking minority in the south might be induced to rise up. There could be assistance from Minutemen in the mountains. But the democratic opposition is too defeated and divided to provide much help. The answer could be an "inside-out" strategy using special forces to take Washington and a few key nuclear bases. Provided the rest of the country was left to get on with its business, there would probably be little internal opposition to a seizure of the capital.

That leaves the substantial problem of an "exit strategy". There is no point in a repeat of 1812. But the experience of America in Japan after the Second World War could provide a model. A period of occupation of five to 10 years could provide an opportunity to inculcate ideas of true democracy, with a fair electoral system based on absolute majority, abolition of the death penalty, introduction of unions into hi-tech industries and a break-up of the Zaibatsu, the overweening corporations such as Microsoft, Exxon and General Electric.

Given time, this rogue superstate might then be able to take its place once again among the family of peace-loving nations.