Even without the use of Saudi Arabia's vast desert expanses to launch a ground invasion of Iraq, the U.S. military would have plenty of room to operate from tiny Kuwait and elsewhere, defense experts say.

There already are more than 12,000 U.S. forces in Kuwait — mostly Army soldiers — training in desert warfare. At least another 14,000 are in other Persian Gulf nations, and the Navy has an aircraft carrier, the USS Lincoln, in the northern Persian Gulf with more than 5,500 sailors and dozens of warplanes aboard.

If President Bush decided to go to war, thousands more forces would flow into the area.

Saudi Arabia was the key to assembling the massive allied force used in the 1991 Gulf War, starting shortly after Iraq invaded Kuwait in August 1990. By February 1991, about a quarter-million combat troops were ready to push into occupied Kuwait and southern Iraq, and the fighting was declared over in 100 hours. Those combat troops were backed by a similar number of support forces, mostly at bases in Saudi Arabia.

This time Saudi Arabia almost certainly will not permit a buildup of U.S. ground forces or strike aircraft on its territory.

Ideally, the United States would position its ground troops on Iraq's perimeter in every direction, said Anthony Cordesman, a military analyst at the Center for Strategic and International Studies. But political realities — especially the rising tide of anti-Americanism in the region — have forced the Pentagon to assume from the start of its war planning early this year that no ground forces will operate from Saudi soil.

"Planning has always been based on Kuwait as the primary point of access," Cordesman said.

Kuwait remains indispensable as a staging ground, despite shootings there that killed one Marine and wounded another on Oct. 8 during a training exercise, and wounded two Army soldiers on Thursday.

It remains possible that the Saudis will allow U.S. support aircraft such as aerial refuelers and surveillance planes to fly from Saudi bases, or at least permit U.S. attack planes to fly through Saudi airspace.

Kuwait, an oil-rich desert state slightly smaller than New Jersey, has hosted a virtually permanent U.S. Army presence since the Gulf War ended. This time it would be the key launching pad for invading ground forces, should President Bush decide force is required to disarm the Iraqi President Saddam Hussein's government.

Already there are more than 7,000 Army soldiers training for war at Kuwait's Camp Doha, a large base about 35 miles from the Iraqi border, and thousands more could be positioned in that area. The Kuwaiti government has condoned off the western part of the country to accommodate American military exercises.

"Kuwait allows you access for heavy forces to Iraq's western desert," Cordesman said. Iraq's own armored forces could not move into position to try to stop the onslaught without risking attack by U.S. planes.

In all, there are about 12,000 U.S. military personnel in Kuwait. The Air Force flies from two Kuwaiti bases: Ali Salem air base about 43 miles northwest of Kuwait City, and Ahmed Al Jaber air base, 47 miles west of the capital.

The Pentagon's current plan for attacking Iraq calls for up to 250,000 troops — land, sea and air, but an invasion might begin with a much smaller force — perhaps 50,000 — from a wide range of bases in the Persian Gulf. The Marines, for example, might stage from Bahrain, headquarters for the Navy's 5th Fleet, and the Air Force would have more bases to operate from elsewhere in the Gulf than it did during the 1991 War.

Jordan, which borders Iraq on the west, is unlikely to allow a buildup of U.S. ground forces on its territory. There has been speculation that U.S. and perhaps British special operations forces are prepared to slip across the Jordanian border to sabotage or destroy Iraqi Scud missile batteries that might be aimed at Israel.

A contingent of U.S. special operations forces conducted a little-publicized exercise in Jordan in October.

To the north of Iraq, Turkey has at least a few air bases that would be useful to U.S. forces. American and British fighter and support planes already fly regularly from Incirlik air base in south-central Turkey. There are no U.S. ground forces in Turkey, although it could be a staging area for special forces.

Bill Arkin, an independent military analyst who studied the U.S. military campaign in 1991, said it is likely that U.S. forces would establish forward air bases inside Iraq, perhaps in areas of the north that are controlled by independence-minded Kurds, and perhaps in the south and the extreme west. Army airborne forces, perhaps, would secure such bases after an initial wave of intense airstrikes elsewhere by U.S. fighters and bombers.

The United States has forces stationed in other countries within striking distance of Iraq — Afghanistan and Uzbekistan, for example — that it did not have in 1991. It also has built up its presence in key Gulf states like Oman; Air Force B-1 bombers operated from an Omani base portions of the air war in Afghanistan.

Tens of thousands of U.S. forces would operate from aircraft carriers and Marine amphibious groups in the Gulf.