If there was any doubt left that the United States was prepared to force the crisis in the Persian Gulf to a conclusion early next year, it was largely erased last week when President Bush announced that he was sending an additional 200,000 U.S. troops to the region.

From inside the Bush administration, the announcement is viewed as another step in a continuing process that began days after Iraqi President Saddam Hussein's forces invaded Kuwait last August.

But the size and timing of the new deployment have started a clock ticking in the gulf that makes it apparent that the administration is prepared to bring matters to a head sometime early next year.

For the administration's planners, this may have been clear some time ago. For the American people, it became starkly clear last week. Bush and his top advisers hope that Saddam will now get the same message and avoid the bloodshed that otherwise seems inevitable.

Bush set the direction of U.S. policy in early August with his initial decisions to deploy troops to Saudi Arabia and push for United Nations resolutions condemning Iraq's invasion and calling for unconditional withdrawal and the restoration of the government of Kuwait. To administration planners, failure to drive Iraq from Kuwait, peacefully or otherwise, is now unthinkable.

"All of the people thought the same way, that not responding would send a very bad signal," a senior administration official said last week in explaining the August decisions. "But responding and failing would send a terrible signal for this whole world order that people are saying might be able to come out of it."

U.S. officials had hoped by now Saddam would show more signs of understanding that the solid phalanx against him means he cannot succeed with his annexation of Kuwait. But so far, the economic sanctions and the united front at the United Nations, including Iraq's old ally, the Soviet Union, have not had the desired effect of forcing Saddam's withdrawal.

Bush still has stopped short of issuing an explicit ultimatum to Saddam, hoping that the unpredictable Iraqi leader will calculate the odds and withdraw in an attempt to hold on to his power. The president and his advisers still hope that Saddam prefers peace to war.

But with the sanctions still not biting hard enough, the newest deployment suggests that the United States will not wait indefinitely for Saddam to withdraw on his own.

On Friday, Defense Secretary Richard B. Cheney indicated that there are no plans to rotate U.S. forces now in the gulf, something that had been talked about in the weeks after the first wave in the buildup began arriving. "No plans to rotate the troops have been announced," a Pentagon spokesman said yesterday. "The current policy . . . is to add to those forces already there."

There will be no substitutions. In other words, the troops there and those on the way are there for the duration.

The duration, however, cannot be indefinite. Having a massive force stuck in and around the sands of Saudi Arabia with nothing to do is hardly the ideal for keeping soldiers, sailors and air force personnel fit and ready. The longer the stalemate drags on, the more problems U.S. commanders in the region will face with boredom, restlessness, morale and readiness.

The longer it goes, the more uncomfortable Saudi Arabia may become with the presence of foreign forces on its soil. The more the crisis continues, the closer it brings the Saudis to Ramadan, the Moslem holy period that begins in March, and in June to the Hajj, the annual pilgrimage to Mecca. Administration officials understand that the religious calendar complicates the crisis.

All of that suggests conflict is unavoidable unless the Iraqis blink, or, conceivably, unless the alliance against Saddam breaks apart in disagreement over, say, an offer to withdraw from all of Kuwait except Bubiyan Island.

While there may be a military and diplomatic logic to the strategy now in place, for Bush it still represents a huge gamble in terms of potential loss of lives, the shape of the world to come and his own presidency.

Up to now the president has enjoyed strong and bipartisan support from Congress, but there were signs after last Tuesday's midterm elections that Democrats may feel emboldened to challenge Bush, if not on the fundamentals of the policy, then more likely on what they regard as the president's failure to prepare the American people adequately for the difficult steps that now appear closer than ever.

That is a line of criticism that frustrates those closest to the president, who argue privately that they "don't know how the stakes could be any more obvious," as one put it last week.

But to his critics, the president has not fully outlined those stakes. He has demonstrated his resolve but not always the full reasons for it. He has talked about resisting aggression, he has invoked Hitler's memory to portray Saddam as a threat to world stability, he has encouraged the notion of a new world order in which the United Nations functions as its dreamers once hoped.

But he has not fully explained why regional conflict today is more dangerous than it was during the Cold War. And he has blurred the economic stakes in part because of criticism that he is willing to plunge the nation into war for the sake of cheap oil.

Along the campaign trail this fall, protesters began popping up carrying signs that said, "No war for oil." Bush brushed them aside, saying the real issue was "naked aggression."

But those close to Bush talk about the economic component of the crisis in a clearer and more realistic way. If Saddam had been left to overrun Kuwait and line up his forces on the border with Saudi Arabia, administration officials feared he could dominate -- psychologically, if not physically -- the nation with the largest oil reserves in the world. The dangers to the world economy are clear, administration officials argue.

"Is this the kind of guy you want to have his hands around the economic throat of the industrialized world?" one official asked. "This is not a matter of going to war for oil. This is a matter of a guy . . . literally having an enormous impact on the world economy."

Bush's decision last week made it clear he has made hard choices in the private councils of his administration. The trip of Secretary of State James A. Baker III suggests that the United States remains successful in keeping its allies on board.

But Bush still faces the task of rallying the American people and assuring that the international coalition will join in taking the ultimate step before his policy is complete. After what he did last week, he has less time than ever.