President Bush's order mobilizing an additional 200,000 troops to the Middle East yesterday makes Operation Desert Shield one of the largest deployments of U.S. fighting forces since World War II, Pentagon officials said yesterday.

When completed, the Army will have 68 percent of its forces overseas, and 34 percent of them will be in the Operation Desert Shield area, a percentage of total forces that an Army spokesman said was higher than the portion deployed in either the Vietnam or Korean wars. Before yesterday's announcement, about 230,000 U.S. military personnel were in the Persian Gulf.

Although Defense Department officials would not discuss the current strength of the additional units, it was clear from the unit names that the Army, Marine Corps and Navy are moving some of their largest and best-trained offensive forces into the region.

The Army contingent of up to 100,000 includes major units now in Germany led by VII Corps commander Lt. Gen. Frederick M. Franks Jr.

The Army's units from Germany are equipped with the latest helicopters and the M-1A1 Abrams tank, the version of the service's premier tank equipped for chemical warfare. The Marines will send about 45,000 men including the elite II Marine Expeditionary Force from Camp Lejuene, N.C., one of the service's largest combat units; and the smaller 5th Marine Expeditionary Brigade, Camp Pendleton, Calif.

The Navy will add three aircraft carriers, each carrying about 5,000 sailors; the 1,500-man battleship Missouri; and an unspecified number of escort ships to the massive Persian Gulf task force it has assembled since the Aug. 2 Iraqi invasion of Kuwait.

The Norfolk Virginian-Pilot last night said the carriers Theodore Roosevelt and America, now training off the Virginia Capes, are likely to be sent to the gulf with eight other Norfolk-based ships. Those range from the repair ship Vulcan, one of the Navy's oldest ships, to the Mount Whitney, the 2nd Fleet's command ship.

Bush also authorized mobilization of three large combat tank units from the Army National Guard. The units are from Georgia, Mississippi and Louisiana. Each contains between 3,857 and 4,298 service personnel, but will undergo additional training before any deployment overseas, Pentagon officials said.

The guard units are "round-out" brigades for the larger divisions. Under the Pentagon's "total force" policy adopted in the mid-1970s, guardsmen and reservists are deployed in any future conflict along with full-time troops, a step that is supposed to keep hometown support behind any combat operation.

"The support of Georgia for the military is historically high and it continues to be high," said Col. Harry Heath, spokesman for the Georgia National Guard. which will mobilized its 4,298-member 48th Mechanized Infantry Brigade. "There's no doubt in my mind that the citizens of Georgia will continue to support this action."

The six large Army units in Germany that will head for the gulf include three armored divisions: the 1st, 2nd, and 3rd, which typically have about 350 tanks and between 13,000 and 17,000 soldiers each.

Also deployed were the 2nd Armored Cavalry Regiment, a smaller unit from Nurenberg that typically would contain about 4,500 personnel and 123 tanks, 26 AH1 attack helicopters and 27 reconnaissance OH-58 Scout helicopters.

The 1st Infantry Division from Fort Riley, Kan., another tank unit, was the largest U.S.-based Army unit designated to be sent to the region.

The National Guard units include:

The 155th Armored Brigade: 3,857 guardsmen, based in Tupelo, Miss. Equipment includes M-1 tanks, M-2 and M-3 Bradley infantry fighting vehicles and assorted artillery. The 48th Mechanized Infantry Brigade: its 4,298 members are part of the Georgia Army National Guard, based in Macon. They have M-1 tanks, Bradley vehicles and artillery.

In September, three companies of support units from the Georgia National Guard, totaling about 500 persons, were sent to Saudia Arabia. They included a military police unit from Atlanta, a transportation company from Augusta and a maintenance company from Savannah.

The 256th Mechanized Infantry Bridge: 4,212 troops, based in Lafayette, La. Its equipment is similar to that of the other guard units.

The 5th Marine Expeditionary Brigade: Based at Camp Pendleton, Calif., its components are similar to the II Marine Expeditionary Force, but smaller, with 4,000 to 8,000 men equipped for a medium-term mission.

The Maritime Prepositioning Ship Squadron 1: A combat-ready squadron assigned to support the 6th Marine Amphibious Brigade or other units. It was described as a relatively small unit.

Staff researcher Ralph Gaillard Jr. contributed to this report.