WASHINGTON — THE brinkmanship of Iraqi President Saddam Hussein, even in defeat, has again raised the slight but unmistakable prospect of American military action in the Gulf.The immediate matter at hand is a United States Air Force escort to protect United Nations nuclear inspectors moving by helicopter into Iraq. But the bigger picture is the unfinished business of the Gulf war - and possibly with Saddam himself. "We've been engaged since May in a sort of messy, nagging end game in Iraq," says Thomas McNaugher, a senior fellow at the Brookings Institution and a reserve Army officer who served in the Gulf. "And the way it will move is toward military force," he says. President Bush and his top aides have been busy playing down that possibility since the Air Force mission was first reported Wednesday morning. Mr. Bush called it just "prudent planning" and not a threat. But he and his spokesmen also made clear that Iraq's compliance with the UN resolutions that authorize nuclear inspections is mandatory - just as with the resolutions that led to the war itself. Failure to comply, said State Department spokesman Richard Boucher, would have "grave consequences." So far, Iraqi cooperation has been minimal. In what US officials have called a "shell game," inspectors are allowed into suspected weapons plants only after a flurry of activity and equipment movement takes place. In the months since the war ended, inspectors for international organizations have turned up surprising indications of the scale and diversity of Iraq's effort to develop nuclear weapons. "All the evidence so far points to a long-term, large-scale, Manhattan Project-type program," says Steven Dolley, research director for the Nuclear Control Institute here, which monitors the proliferation of nuclear weapons. During the war, he adds, "it was pretty much known that Saddam wanted the bomb, but not how much effort and money he was pouring into it and how far [along] he was." Yet Iraq continues to rebuff attempts by UN teams to make snap inspections of suspected sites for weapons work, even though Iraqi leaders agreed on complete and unconditional access for inspectors as part of the cease-fire agreement that ended the war. Last week, the top United Nations inspector, Rolf Ekeus, said that the inspection teams had not yet been able to piece together the Iraqi "master plan" for producing the nuclear, biological, and chemical weapons known as "weapons of mass destruction." The Iraqis appear to be playing games. Inspectors announced last week finding that Iraq had reassembled two Scud missile launchers, taken apart as required under the cease-fire accord. At first, Iraq required the inspectors to use Iraqi helicopters with Iraqi pilots. On Monday, Iraq decided to allow the UN team to use three helicopters and crews supplied by Germany but restricted their movements. This week, the US dispatched an Air Force wing to Saudi Arabia so that, if Iraq failed to open the door to the inspection teams completely, American jets and helicopter gunships could be sent along to protect them. The US also is sending the Saudis some Patriot missiles, in case hostilities resume. The scenario this mission seems to be preparing for is that the helicopters with the United Nations teams can be launched into Iraq without Iraqi permission and the military jets can return any hostile fire. Some analysts speculate that the return fire might be directed to the Iraqi command-and-control bunkers and perhaps against Saddam himself. "Going after him becomes an option again for the first time since February," says Daniel Pipes, director of the Foreign Policy Research Institute. Few believe that Saddam wants to provoke hostilities again. He is more likely engaged in brinkmanship. But his judgment about where the brink lies is notoriously faulty, notes Dr. Pipes. "At this point, so far, he has responded quite nicely to threats," says Mr. McNaugher of Brookings. "But you can't bluff this guy, and I think Mr. Bush knows this." The continuing business of the Gulf war includes protecting the Kurdish and Shiite minorities inside Iraq, guarding Kuwait from renewed attack, and stripping Iraq of the capacity to build weapons of mass destruction. Bush has also added the removal of Saddam from power as a condition for dropping economic sanctions against Iraq. The sanctions are beginning to erode, says McNaugher. If necessary, military force against Saddam could, ironically, be more humane to the Iraqi people than continuing sanctions, he says. Pipes says that Saddam's isolation has virtually eliminated Iraq as a regional threat.