O.C. Marines Pour Into Saudi Desert in Showdown : Gulf crisis: Contingent from El Toro and Tustin stations is expected to hit 5,000 this week.

The first Marine Corps advance team from Orange County and elsewhere in Southern California landed in Saudi Arabia on Tuesday to pave the way for thousands of troops expected later in the week, military officials in Washington said.

“This is the first significant combat force being sent into the country,” a defense official said, explaining that U.S. forces first sent to Saudi Arabia were lightly armored infantry, while the Marines have tanks, attack helicopters and heavy artillery.

“When the Marines come in, there is going to be a dramatic increase in numbers of U.S. troops there as well as sustained combat capability,” said the official, who asked not to be identified.

The team is part of the Camp Pendleton-based 1st Marine Expeditionary Force, the 3rd Marine Aircraft Wing from El Toro and the 7th Marine Expeditionary Force headquartered at the Twentynine Palms Marine Air-Ground Combat Center in San Bernardino County.

“This is the advance team for the Marines, and they are the first to arrive,” said Lt. Col. Stu Wagner, a Defense Department spokesman.

The advance party will “go in and arrange for logistics, scope the place out, figure out where are we going to put all this stuff, set up communications,” said Chief Warrant Officer Randy Gaddo, a Marine Corps spokesman in Washington. “They look at what needs to be done to have an orderly flow, because you’re talking about a large amount of Marines coming soon.”

Gaddo said he could not say exactly how many people comprise the advance team--or how many personnel from each base--but another Washington source set the number “in the hundreds.” It includes personnel from the El Toro Marine Corps Air Station and the Tustin Marine Corps Helicopter Station.

The advance team joins several thousand troops from the U.S. Army’s 82nd Airborne Division already in Saudi Arabia. In addition to the advance team, the Pentagon on Tuesday confirmed reports that air and ground combat troops, as well as support personnel, have left Southern California Marine Corps bases for the Persian Gulf since President Bush ordered troops there Aug. 7.

While military officials have steadfastly refused to say how many U.S. troops have been dispatched to the Persian Gulf, Gaddo said an expeditionary force can number “anywhere from 18,000 to 45,000.”

From Orange County alone, as many as 5,000 Marines will be converging on the Middle East by the end of this week, a high-ranking military source said Sunday from Washington. That source said large numbers of fighter jets, bombers and transport planes from El Toro would be flying directly to join the U.S.-led action against Iraq known as Operation Desert Shield, with stops for refueling.

A small group of officers and enlisted personnel from both El Toro and Tustin were part of the advance team that arrived Tuesday, the military official said. Combined, there are about 12,000 soldiers and support staff at the two bases.

However, much of the cargo and troop-loaded helicopters from the Tustin base would be sent by ship because of the limited number of U.S. Air Force transport aircraft available to shuttle the equipment to the Persian Gulf.

In the past two days, massive troop carriers--C-141 Starlifters and C5-A’s--could be spotted landing at and departing from El Toro, where officials announced that airfields that normally shut down by 10 p.m. would essentially be open around the clock.

“Local residents may experience an increase in the noise level around Marine Corps Air Station El Toro intermittently 24 hours a day until further notice,” said Marine Master Sgt. Steve Merrill, a base spokesman. “The extended airfield operating hours are necessary due to operational commitments. That means, while we do our jobs.”

The El Toro station is home to about 50 F/A-18 Hornet fighter jets and 12 A-6E Intruder fighter-bombers, as well as about a dozen DC-130 tankers, the corp’s largest transport airplane, capable of carrying 120 to 150 troops. It is used for aerial refueling.

From elsewhere in the country, U.S. Air Force support also arrived Tuesday in the Middle East. It included KC-10 and KC-135 tanker aircraft, which are used for in-flight refueling; RC-135 reconnaissance aircraft and E3-A Airborne Warning and Control System (AWACS) aircraft, which provide radar detection.

Also en route to the Persian Gulf are elements of the 4th Marine Expeditionary Brigade, headquartered in Norfolk, Va., which includes ground combat and support troops from the 2nd Marine Division and the 2nd Force Service Support Group at Camp Lejeune, N.C., and air combat troops from the 2nd Marine Aircraft Wing at Cherry Point and New River, N.C.

Times staff writer Matt Lait and Times Wire Services contributed to this story.