ABU DHABI, U.A.E., AUG. 20 -- Defense Secretary Richard B. Cheney announced today that the United Arab Emirates had agreed to allow U.S. military forces to operate from its bases, marking what Cheney called "a significant departure" for this Persian Gulf government.

Though U.S. troops began arriving here almost a week ago, the agreement between Washington and the Emirates was made public today during a frenetic 15-hour tour of five gulf nations where Cheney was attempting to galvanize multinational military efforts to prevent Iraqi President Saddam Hussein from attacking Saudi Arabia or any other Arab nation.

Defense Department officials said they believe anxiety over Iraq's military capabilities have intensified since Cheney's first visit to the region just days after Iraqi forces invaded neighboring Kuwait Aug. 2.

Cheney said today that the heightened tension has fostered a greater willingness among most Arab leaders to participate in defensive military operations and grant the Americans more liberal use of their facilities for military missions aimed at protecting Saudi Arabia.

For most of the Arab nations, which historically have refused to discuss their military agreements, merely acknowledging the presence of foreign forces has been a dramatic change.

"It's a big step for the Emirates," said Cheney, the highest-ranking U.S. official ever to visit this nation, which is an alliance of seven sheikdoms located in the southern gulf region. "It is a measure of the seriousness of the situation. They're deeply concerned. Their very existence is threatened by Saddam Hussein."

According to Defense Department officials who are accompanying the secretary, the leaders of Saudi Arabia and Oman asked Cheney to take a last-minute detour this afternoon to visit the leaders of Qatar, which is considered to be the most recalcitrant of the Persian Gulf nations.

After a 45-minute meeting with Qatar officials in the opulent royal palace in the capital city of Doha, a Cheney spokesman described the visit as "very successful" but would not elaborate.

U.S. military units, including 16 C-130 transport planes and a support staff of 575 military men and women, began arriving in the Emirates almost a week before Cheney came today to announce the agreement.

The Air Force has positioned its squadron of C-130s and support personnel at the Emirates' Bateen air base near the edge of this capital city. The location is critical to U.S. airlifts of supplies and equipment in the gulf region. Air Force officials say that Operation Desert Shieldrequires the movement of so many tens of thousands of troops and millions of tons of equipment that Saudi Arabian airfields are overtaxed.

Cheney, after a sweltering tour of U.S. operations here, said that although the military cooperation announced today is based on the current "very real threat" in the region, he believes the efforts will lead to greater long-term cooperation between many Arab nations and the United States.

While providing greater U.S. access to their nations, many Arab leaders, including those in Saudi Arabia and Bahrain, are pressing Washington for more arms sales.

Cheney said the United States is considering providing additional military equipment to some of those nations and is discussing such requests with Arab leaders during his four-day trip, which includes stops in Saudi Arabia, Bahrain, the Emirates, Oman, Qatar and Egypt.

Cheney is expected to negotiate agreements that would allow Saudi Arabia to buy 24 of the U.S. Air Force's most advanced version of the F-15 fighter plane. In the past, members of Congress have opposed selling the Arab nations the most sophisticated version of that plane.

Between sessions in some of Middle East's most imposing royal palaces, Cheney visited sweating troops now operating at the U.A.E. airfield near here.

Within 48 hours after the first U.S. Air Force C-130s touched down on the dusty Bateen Airport, the U.A.E. government began erecting a village of small barracks buildings for personnel of the 314th Tactical Airlift Wing, normally based in Little Rock, Ark.

As Cheney walked across the sweltering airfield, a crowd of Air Force officers and enlisted men and women gathered in a massive hangar bay to greet him. A spray-painted welcome sign on a large plywood board leaned against the hangar doors.

Nearby, clusters of Air Force personnel stepped out of their air-conditioned barracks to wave at Cheney.

A 26-year-old captain said the heat was "unbearable, it's like walking into an oven." She said temperatures can reach 130 degress.

The Air Force personnel said they spent their first two nights sleeping in the hot hangars. But by the third day, local workers had cleared desert scrub brush and had begun erecting the barracks. As Cheney's entourage boarded buses and limousines to leave the airfield, a crowd of airmen standing in front of their barracks shouted, "Tell them to send pillows."