International rules lose their validity when widely flouted or when superseded by new strategic realities. The U.N. Charter’s curbs on the use of military force had suffered both fates long before George W. Bush became president. America’s pattern of acting without Security Council authorization-justifiably, in at least some cases-dates back at least to the 1962 Cuban missile blockade and has marked U.S. military activities in Vietnam, Lebanon, Grenada, Panama, and Nicaragua.

President Clinton in 1998 bombed Iraq despite the objections of two permanent Security Council members, Russia and France. He also sent bombers to stop Serbia’s "ethnic cleansing" of Kosovar Albanians in 1999, over Russia’s objection and thus without Security Council approval. These and dozens of other theoretically illegal (mostly unjustified) military attacks by other nations around the world over the past five decades reflect "geopolitical realities too strong for a legalist institution to withstand," as Michael J. Glennon writes in the May-June issue of Foreign Affairs.

Any vestige of the Security Council’s claim to be the guarantor of international peace and security has now been wiped out by its paralysis in the face of the radically new strategic threats that have become so apparent in recent years. These are the mortal danger to America and the rest of the civilized world posed by efforts of hostile despots to obtain nuclear and biological weapons (or the capacity to make them) and the related risk that such weapons could fall into the hands of jihadist terrorists bent on destroying Western civilization. These realities have made the U.N. Charter’s foundational rule against any nation’s military intervention in any other sovereign state’s internal affairs-affairs once thought to include the state’s right to make or buy whatever weapons it chose-into a dangerous anachronism.

Now President Bush has shattered with finality the illusion that the U.N. Security Council had any real power to enforce the limits on military intervention that were spelled out in the U.N. Charter. Meanwhile, the rupturing of NATO’s unity over Iraq eliminates that tattered alliance as a fallback source of international legitimacy.

Does this mean that Bush recognizes no legal restraints at all on America’s use of its unmatched military power? That he claims a right to go to war against any nation that displeases him or stands as an obstacle to his designs? That international law is dead, and has now been buried by the same United States that has long purported to be its champion?

That is the fear voiced by much of the world. It may also be the hope of some neoconservative hawks, who seem to like the international law of the jungle just fine, as long as us good guys carry the big stick.

Bush should prove them wrong. He should seize his moment of military triumph as an opportunity, not only to threaten rogue states that sponsor terrorism and that seek nuclear and biological weapons, but also to reassure allies and potential allies. This he can do by specifying in some detail a vision of international law that eschews wars of aggression while retaining the freedom to confront today’s grave new strategic perils.

This does not mean letting the U.N. keep us from helping Iraqis choose a decent government or from deciding when to use military force. But it does mean pledging and demonstrating scrupulous adherence to the letter and spirit of generally accepted international rules that retain their validity, such as the Geneva Conventions and the prohibition of aggressive wars. It also means being generous in victory, both to nations that denounced our invasion (excepting the ones that aided our enemy) and to the innocent Iraqi civilians who have been hurt, and whose family members have been killed, as unintended consequences of our military operations. And it means helping the U.N. and other international institutions do the things that they do tolerably well, such as providing humanitarian relief and verifying American discoveries of weapons of mass destruction-discoveries that will otherwise be widely dismissed as phony.

But those who condemn Bush for using pre-emptive force without Security Council approval are unrealistic and (in many cases) hypocritical. "We are at a moment in world affairs when the essential ideas that govern statecraft must change," Philip Bobbitt writes in his stunningly original book, The Shield of Achilles: War, Peace, and the Course of History. "For five centuries, it has taken the resources of a state to destroy another state…. This is no longer true."

As President Bush said in his "National Security Strategy of the United States," in September 2002: "Now, shadowy networks of individuals can bring chaos and great suffering to our shores for less than it costs to purchase a single tank," and seek to "turn the power of modern technologies against us" by attacking us with doomsday weapons covertly obtained from unknown sources.

It is largely to prevent such a catastrophe that President Bush has asserted the right not only to target states that sponsor terrorism but also to "act pre-emptively" to disarm or depose hostile regimes that seek to threaten us with nuclear or biological weapons. The latter policy cannot be squared with the U.N. Charter’s aspirational language that authorizes use of military force in self-defense only "when an armed attack occurs." But this does not make the invasion of Iraq illegal. Aside from Saddam Hussein’s unique history of violating Security Council resolutions, the "armed attack" rule’s literal meaning has been so widely disregarded and has become so inadequate to our self-defense needs, that the rule retains little if any force as international law.

The U.N. also cannot act to prevent genocide and crimes against humanity within states, as it has demonstrated in Rwanda, Kosovo, and elsewhere. And the unanimous support of NATO’s members for the bombing of Serbia and Kosovo (a Serbian province) implicitly recognized that the U.N. Charter’s doctrine of absolute territorial sovereignty-which contained no exception, even for genocide-had been qualified by evolving principles of international humanitarian law.

Today’s world is simply too dangerous, and in some places too barbaric, for America to give any international body a veto over its use of military force. We need not be embarrassed to say so, because our own interest in preventing rogue nations and terrorists from plunging the world into nuclear anarchy is entirely consistent with the interests of other civilized nations.

But those other nations do not trust America to use its unmatched power responsibly and wisely. And we will need their trust. In Bobbitt’s words, "There’s not enough force in the world to rule over 200 states that hate us, nor can we defeat terrorism without widespread and genuine cooperation. We should take this opportunity to set clearly articulated standards for intervention." Such standards would make the Bush Doctrine less alarming to states that we have no intention of attacking. China, for example, "must know that an intervention to rescue Hutu civilians in Burundi or to trap Al Qaeda leaders in Afghanistan is not preparation for intervention on behalf of Tibetans," says Bobbitt.

Bush could begin by pledging to abide by the following rules (mine, not Bobbitt’s), which seem implicit in his September 2002 "National Security Strategy."

The United States will use military force only:

1. When dictated by urgent, specifically defined self-defense needs, including the need to disable anti-American terrorists or to pre-empt acquisition of nuclear or biological weapons by despotic rogue regimes;

2. As part of a coalition of states to enforce Security Council resolutions or to halt ongoing, pervasive violations of international humanitarian law; or

3. As a carefully limited and proportionate response to threats to other vital interests unrelated to profit, commercial advantage, or acquisition of territory or resources.

Bush could also demonstrate adherence to the spirit of these rules by pledging, more explicitly than he has, to use Iraq’s oil and other assets solely for the benefit of the Iraqi people. And, of course, by finding those Iraqi weapons of mass destruction.

In time, perhaps, a great-power consensus may emerge, recognizing such self-imposed rules as universal principles well-adapted to current strategic realities. The objective, as Bobbitt says, should be "saving, rather than sacrificing, international law."

Correction: In my April 12 column, I erred in saying that data in a Century Foundation study suggest that white and Asian college applicants rejected because of racial preferences may be less affluent on average than the black and Hispanic students thereby admitted. The study’s authors have informed me that their data do not support this assertion. It was an incorrect and unwarranted inference on my part from their statement that basing admissions solely on grades and test scores would increase socio-economic diversity. I regret the error.