Updated

U.S. Marines rode massive green hovercraft last week onto the Kuwaiti shore. But instead of assaulting hostile Iraqi troops, they joined Kuwaiti allies for a three-week exercise in the desert.

Fighter jets from the USS Abraham Lincoln flew overhead, not part of the exercise, but on their way to enforce a "no-fly" zone in southern Iraq.

Engineers in Qatar, meanwhile, are finishing a new forward command post for the U.S. Central Command -- the men and women who would lead a war in Iraq. They're expected to arrive in November to direct another exercise from the low-profile buildings camouflaged as sand dunes.

Special operations forces have put up tents at a new base in Djibouti, across the Red Sea from Yemen. In Kuwait, part of an armored infantry brigade from Fort Benning, Ga., sits within 28 miles of the Iraqi border -- a 10-hour drive to Baghdad.

U.S. military spokesmen insist the exercises and deployments are routine, or part of the war against terrorism. But there is little doubt these forces could be used in an invasion of Iraq to remove President Saddam Hussein.

During a visit to Kuwait last week, Central Command's Gen. Tommy Franks said his men "are prepared to do whatever we are asked to do."

While the governments of Bahrain, Qatar, Kuwait and Saudi Arabia refuse to discuss military matters, their citizens bear witness daily to the U.S. military presence in the region.

The Kuwaiti government ordered gas masks for all civil servants and authorized their sale to civilians. Troops have rolled out Patriot missile batteries to defend against possible Scud missile attacks.

"From what we're seeing, it looks like something is going to happen, but it's hard to know exactly what," said Bader al-Otibi, a government worker who was taken prisoner during the Iraqi occupation in 1990. "I'm against war, but I'm also against Saddam."

Along the featureless, rolling desert that is shared by Kuwait and Iraq as a border, unarmed U.N. monitors stand guard in a 10-mile-wide demilitarized zone. An electric fence and anti-tank trenches mark it, but there's little to slow an invading force.

Experts differ on the number of troops needed to invade Iraq -- estimates vary from 50,000 to 350,000, depending on the strategy. Deployments already planned would bring the number of troops in the region to near 50,000 by November, which coincides with a U.S.-proposed deadline for Iraq to comply with U.N. resolutions.

U.S. military personnel, with their close-cropped hair, military-issue luggage and incongruous civilian clothes, are already in hotels in Bahrain, Qatar and Kuwait.

F-16 fighter jets roar over Qatar's capital, Doha, and vans full of troops shuttle between the 5th Fleet's headquarters in Juffair, Bahrain, and the international airport, where the U.S. Navy maintains a special terminal for aircraft that fly to the USS Abraham Lincoln and other regional bases.

The aircraft carrier USS Harry Truman, leading a third battle group, is scheduled to be within striking distance of Iraq in November to replace the USS George Washington battle group, Pentagon officials say, bringing the total U.S. naval forces in the area to more than 20,000 sailors and 255 aircraft.

The Marines, in Kuwait for the "Eager Mace" exercise, make up the 11th Marine Expeditionary Unit, an amphibious invasion force of 2,200 troops. A similar force accompanies most carrier battle groups, meaning 6,600 Marines will be in the region in November.

The U.S. Air Force keeps 6,000 personnel and an undisclosed number of planes at Saudi Arabia's Prince Sultan Air Base; 1,700 troops at Incirlik, Turkey; and 3,300 at the al-Udeid Air Base in Qatar, currently home to refueling planes. Several thousand more U.S. Air Force members operate from two air bases in Kuwait and hundreds of ground support workers are in the United Arab Emirates and Oman.

Part of the 3rd Brigade, 3rd Infantry Division from Fort Benning is wrapping up a routine six-month tour as Kuwait's defenders, waiting to be relieved in November by the 2nd Brigade from Fort Stewart, Ga., a Central Command spokesman said. A typical armored infantry brigade numbers between 2,500 and 3,000 troops.

The Fort Benning troops, like the USS George Washington battle group's sailors, could have their stay extended, military spokesmen said.

Tanks and armored personnel carriers for another brigade sit ready at Camp Snoopy in Qatar and the U.S. Military Sealift Command recently hired cargo shops to carry more combat equipment to the region.

Apart from Djibouti, where U.S. special operations forces have set up a base, residents of Eritrea have reported U.S.-financed construction at former Soviet air and naval bases in their country on the Red Sea.

Sitting at a Starbucks in Kuwait City, Abdullah al-Mutairi said he thinks war is inevitable and necessary.

"Kuwait has a lot to lose from a war and Kuwait has a lot to lose if Saddam stays in power," al-Mutairi said. "It is better we choose war than to continue to live in fear."