President Bush's announcement that he was doubling American troop strength in Saudi Arabia was no mere deployment decision. Despite subsequent administration protestations to the contrary, it was an executive declaration of war.

In America, however, the legislature is supposed to declare war. That is why Sen. Richard Lugar is entirely right that Congress ought to be called back into session to debate a resolution to declare war or to give the president some equivalent authority to use force, if he deems it necessary, against Iraq.Congress has a legitimate and essential role to play in the affair. The issue is not just constitutional. It is political. War cannot be waged successfully without popular support. If Congress is not consulted, it will simply criticize, fatally compromising any military action that runs into the slightest difficulty or delay, as all military operations must.

Sen. George Mitchell, Rep. Les Aspin and other congressional leaders are resisting the idea on the grounds that it is premature to vote when the question of war is hypothetical. But there is nothing hypothetical about the prospect of war. The new deployment creates an unstable equilibrium.

You do not - you cannot - put 400,000 American soldiers in the Arabian Desert for defensive purposes. The logistics are a nightmare. Morale is a wasting asset. And Saudi Arabia, already unstable, cannot cope indefinitely with the shock of such a massive foreign force.

It is therefore understood by all parties in the region, if not yet by Congress, that this is a use-it-or-lose-it deployment. By January, the president will have only two choices. He can use the 400,000 troops to make war. Or he can begin drawing them down, which will be read in the Middle East, correctly, as an American capitulation.

Congress should vote up or down on a resolution authorizing the president to use any means necessary, including force, to get Iraq to withdraw from Kuwait. The only possible reason for delay would be to wait for a U.N. resolution to the same effect. A Security Council resolution authorizing force would help the president get a similar resolution through a Democratic Congress.

It remains a principle of Democratic faith, though a mystery to me, that Americans should care what the world thinks about American foreign policy. Indeed, there is something crazy, truly crazy, about a secretary of state going around the world begging and bribing a half-dozen countries (China, the Soviet Union, France, Turkey and others) to allow - allow! - American boys to fight and die in the sands of Arabia.

Yet such is the current American fascination with multi-lateralism that this absurd activity is considered normal. In fact, when Secretary James Baker returned with the most oblique and grudging expressions of permission, he was praised.

Americans, Democrats in particular, feel morally relieved when foreigners bless our works. Why they should feel better if an American commitment is blessed by Deng Xiaoping and the butchers of Tiananmen Square is beyond me. But it is a fact. If fight we must, we want the U.N. flag fluttering beside us.

The idea that U.N. sanction gives an action some higher morality is nonsense - but widely held nonsense. Indeed, in the early stages of the crisis, U.N. support disarmed the left. "What slowed people like me from coming out against this," said Todd Gitlin, ex-president of Students for a Democratic Society, preparing for a new anti-war crusade, "was seeing the need for collective security."

Fine. It may be a tactical necessity to wait on the Security Council, but there is no other warrant for delay. It is important for Congress to declare itself on the gulf as soon as possible. The operative word is declare. Expressing itself, gassing off about the agony of it all, simply won't do. The country needs decisions. The worst thing Congress can do is simply to debate the issue without resolving it, i.e. without coming to a vote on the use of force.

Naturally, the congressional leadership has chosen just that course. It has decided to hold hearings on the Gulf. There are no plans for a vote. That means that Congress will be airing, for all the world and Saddam to see, American doubts without allowing them to be followed by an expression of American resolve.

On Nov. 8, the president, in effect, abandoned the containment option (waiting for anti-Iraq sanctions to work). His calculation is that Saddam can hold out far longer than can the coalition arrayed against him.

That calculation - and the war policy that follows from it - may be wrong. If it is, now is the time for Congress to say so. Congress should debate, then either approve the war policy or stop it now. There certainly is enough time. War will not start before the year is out. The time to decide the issue and take responsibility is not at the last possible moment, not after the first Americans have died under fire, but now.