Rarely in the postwar world have the issues been as clear as they are in the gulf crisis today. Yet rarely has the debate been more muddled.

After all, this is not some morally murky war of national liberation, but unprovoked, out-of-the-blue, 1930s-style aggression. It did not happen in some marginal corner of the world like Southeast Asia, but in the world's oil treasure house.And the adversary is not some morally ambiguous liberator like Ho or Castro, but a usurper and a thug, a man who has already sacrificed a million lives for control of half the width of one waterway.

Responsibility for the muddiness of the debate lies with the Bush administration. Presented with the easiest moral and strategic case in 45 years - easier than Korea and Vietnam, easier than Grenada and Panama - Bush has been so clumsy in advancing his case as to have nearly discredited it.

The aim of our gulf policy is to defeat Saddam, at the minimum by forcing his unconditional withdrawal from Kuwait. But, complain the critics, the president never adequately explained why Saddam must be stopped. Is it oil? Is it preserving peace in the gulf? Is it establishing the basis for a new post-Cold War order?

The implication is that it must be one or the other. If the president invokes sometimes oil, sometimes order, this is taken as evidence of insincerity. Which is it?

The answer, it is blindingly clear, is all of the above. To imply that these goals are somehow mutually exclusive is nonsense. Any one alone might justify American intervention. The three together add up to an overwhelming self-reinforcing case.

1. Oil: Control of the Arabian Peninsula gives Saddam control of half of the world's oil reserves. That gives him the power to manipulate production to create buying panics, shortages, recession, or whatever world economic shock suits his economic or political goals of the moment.

If preventing half of the world's oil reserves from falling into hostile hands and preventing the hardship and extortion that such dependency brings is not a vital American interest, then it is hard to see what the phrase "vital interest" can possibly mean.

Indeed, the United States has already declared that preventing such a calamity is not just a vital interest but a casus belli. Who declared that? Not Bush but Jimmy Carter, the most dovish president of this century.

The Carter Doctrine, enunciated Jan. 23, 1980, declared that "an attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America. And such an assault will be repelled by any means necessary, including military force."

2. Peace: Saddam's control of oil supplies would allow him to impose a huge tax, payable to him, on every American oil consumer. That would impoverish us. But more important, and worse, it would enrich him.

As in the past, his new and now fabulous wealth will go directly into his military machine. That will make him not only King of the Gulf, but undisputed hegemon of the Middle East.

His immediate aim will be to break those pro-Western Arab regimes that had the audacity to oppose him and the foolishness to rely on the United States.

One day, the Americans will leave Arabia. If on that day Saddam remains, the Saudi royal family will not last a month. Hosni Mubarak of Egypt, the linchpin of the American position in the whole Middle East, will not last much longer.

The smaller gulf states will either be subjugated or physically absorbed, Kuwait-style. Jordan will be next. Ultimately, a new and perhaps nuclear Arab-Israeli war becomes inevitable.

As the richest dictator in history, however, Saddam will not just convulse the Middle East. He will acquire the reach to threaten the world: weapons of mass destruction (nuclear, chemical, biological) and the missiles to deliver them.

Within 10 years, hardly the far-off future, Saddam (age 53) will have nuclear weapons. And last year, Iraq tested a three-stage ballistic missile. Which means that by the end of the decade we will be facing a hostile power with unlimited wealth and nuclear weapons able to reach any city on Earth. That is a very concrete threat, threat enough to warrant breaking this man's sword before it can be used.

3. Order: Forget about woolly New World Orders. Keep your eye on the threat. Saddam is but the first of many coming threats in the coming age of weapons of mass destruction. He is a crucial test case.

If a small, ruthless, heavily militarized regime can stand up to a global blockade, a united Security Council, a majority of the Arab League, the opprobrium of the entire world, the threats of the great powers, and half-a-million troops massed against it in the desert - and still emerge intact and in possession of the fruits of its aggression, the message to every other potential aggressor and victim will be clear: There are no rules in the post-Cold War world. The great powers are preoccupied. America has gone home. Welcome to the 1930s.

Our children will curse us.