In 1950, the United States assembled a coalition of nations under the UN flag to repel the invasion of South Korea by the North. Forty years later, it did the same to repel the invasion of Kuwait by Iraq. In neither case was it obliged to do so: as South Korea and Kuwait were entitled under international law to defend themselves, so the Americans were entitled to come to their aid. But it chose to seek the UN's imprimatur, just the same.

No other country has shown the same deference. Of the two dozen or so other major international conflicts to occur since the UN's founding, not one was carried out under the Security Council's authority. Russia did not ask permission to invade Hungary, or Czechoslovakia, or Afghanistan. China did not ask permission to invade Tibet. India did not ask permission to invade Pakistan, and Pakistan did not ask permission to invade India. Syria did not ask permission to invade Lebanon. France and Britain did not ask permission to invade Egypt in the Suez crisis, and none of the Arab countries ever asked permission to attack Israel, whether in 1948, 1956, 1967 or 1973.

For that matter, even the United States did not ask permission to invade Grenada, Panama and Haiti, or to defend South Vietnam from invasion by the North -- though their interventions were in every case on far more principled grounds, and in all but the last case to happy effect.

The Kosovo intervention, more recently, was also carried out without UN sanction.

If the United States does go to war in Iraq, on the other hand, it will once again do so, at least arguably, with the Security Council's authorization: whether the "serious consequences" threatened last November under Resolution 1441, or the more explicit approval of "all necessary means" to compel Iraq's compliance with the Council's many previous resolutions demanding it disarm, all the way back to the ceasefire that ended the Gulf War.

But even if you take the contrary view, that the failure to obtain assent to yet another resolution somehow negates all the others, it is difficult to see how this would count as some sort of "precedent," as so many allege. As precedent, it is labouring under the handicap of having been set many times before. The more arresting precedent was the first president Bush's decision to seek the UN's authority for the first Gulf War, after a period of 40 years in which no country had felt obliged to do the same. Conversely, if it is a convention that states must seek the approval of the United Nations before going to war, it is a convention that has been observed on only two occasions, and by just one country.

The lesson we should draw from this is not merely of the absurdity of the "precedent" argument -- as if precedent had ever guided any country in the determination of whether to go to war. (Is it the absence of precedent, as our Prime Minister appears to believe, that prevents China from invading Taiwan? Or is it that the Taiwanese are armed to the teeth?) It is the equal nonsense of invoking the United Nations as the guarantor of international peace and security. Not only did each of the above conflicts take place without its approval, but the UN did nothing to stop them. The sole exception was Suez, and then only because the Americans put them up to it.

True, we have had half a century of peace between the great powers, not counting the proxy wars in which they periodically engaged. But again, this had nothing to do with the UN, or peace treaties, or international law. It was not the UN that deterred the Soviet Union from attacking the West: it was the threat of nuclear annihilation. It was not the UN, or the European Union, that preserved the peace in Europe, after centuries of conflict. It was the democratization of the former combatants, notably Germany.

The UN has neither proved sufficient to prevent war, where it has occurred, nor necessary, where it has not. This is no accident. It is a paradox woven from its own premises. International law is very good at preventing the outbreak of war between, say, Italy and Norway: democratic countries that observe the rule of law in their own affairs and are disposed to be bound by it abroad. But these are the very sorts of country that are least likely to go to war with one another in the first place. On the other hand, the countries that are most likely to make war -- dictatorships, particularly rogue states -- are the least likely to be constrained by the niceties of international law.

It is not to the United Nations, or to international law (the two are not necessarily synonymous) that we should look for our collective security. Rather, it is military power, in the short term, and the spread of democracy, in the longer. As it happens, that is just what the Americans have concluded.