Operation Desert Shield has triggered the largest airlift ever undertaken by the U.S. military, the Defense Department announced yesterday. In two weeks, more than 1 billion pounds of ammunition, weapons, food and other supplies has been shipped to American forces in the Persian Gulf.

"We've moved a Midwestern town the size of Lafayette, Indiana, or Jefferson City, Missouri. But we've also moved their cars, trucks, food, household goods and water supply," Gen. Hansford T. Johnson, commander in chief of the U.S. Transportation Command and Military Airlift Command, said in a briefing at the Pentagon.

The airlift has surpassed in intensity the Berlin airlift of 1948 and the prodigious effort to keep troops resupplied during the Vietnam War. The materiel now in Saudi Arabia or en route is equivalent in weight "to 400,000 Chevrolets," Johnson added.

Johnson's detailed account underscored the logistical magnitude of transporting and sustaining an American military force that may exceed 100,000 troops and 50 naval ships by the end of the month, according to military sources.

The Pentagon, for example, is using all but a handful of its 284 C-5 and C-141 transport planes in the Persian Gulf area operation. It also has pressed into service 38 civilian cargo and passenger planes and 79 military and civilian cargo ships.

"This exercise is going very well right now from a transportation standpoint," Johnson said. "We're fortunate we didn't have to fight our way in . . . . We've had no major surprises."

The Defense Logistics Agency (DLA), the Pentagon's chief supply agency, has been operating 24-hour-a-day emergency supply centers nationwide since Operation Desert Shield began, ordering such items as tens of thousands of doses of malaria drugs and $50 million worth of chemical warfare masks and coveralls. The DLA also has asked three uniform factories -- one in Philadelphia and two in Puerto Rico -- to switch from standard jungle green fatigues to sand-colored desert uniforms. The number of new uniforms requested: 400,000.

The military has ordered thousands of gallons of sand-colored paint for tanks and other equipment as part of a massive camouflage job now underway at Fort Hood, Tex., and other posts. Of major units deployed to Saudi Arabia, only the 24th Infantry Division (Mechanized) already has desert camouflage schemes.

The military also is scrambling for fuel as a result of the increased tempo of operations and long-distance transportation requirements. Air bases that typically burn 1 million to 2 million gallons of jet fuel in a month are "burning that amount in a few days now," said Col. Grath Horne, deputy director of the Defense Fuel Supply Center.

The demands of a modern military force can been seen in the grocery list of the aircraft carrier USS John F. Kennedy and its seven escort ships before leaving Norfolk for the Middle East last week. The Kennedy group asked the local Navy supply center for 2 million fresh eggs, 185,000 pounds of hot dogs, 400,000 pounds of hamburger, 300,000 pounds of french fries and 250,000 pounds of chicken, according to a Navy public affairs officer.

The Norfolk supply center loaded 22,000 tons of food aboard the eight ships, which took on 3.5 million gallons of diesel fuel and -- for the Kennedy's aircraft -- 2 million gallons of jet fuel. The supply center also reported selling $1 million worth of hardware and office supplies in four days, an amount typically sold in a month; among the orders was 16,000 dog tags.

For the enormous amount of water required by desert operations, the Army has been designated chief water bearer for the four services, according to Gen. Gordon Sullivan, Army vice chief of staff. The Pentagon operates on a rule of thumb that requires an average of 20 gallons a day per soldier for cooking, hygiene, washing, drinking and vehicle radiators. For 100,000 troops, that would mean a daily demand of 2 million gallons. To supplement Saudi supplies and bottled water, the Army has several types of purification plants that are being moved to the gulf.

The smallest plants can desalt and purify 400 gallons an hour, according to Maj. Peter Keating. Larger units, typically assigned to corps, can purify 150,000 gallons a day or desalt and purify 110,000 gallons a day. The largest plants are mounted on barges and can purify 300,000 gallons a day or desalt and purify 125,000 a day; two of those barges are now en route to the gulf.

The nerve center of the military's transportation effort is the crisis action center at Scott Air Force Base, Ill. Huge screens track as many as 200 airplanes at a time as they arc over the Atlantic Ocean and into Saudi Arabia. Military officers have dubbed the effort "the aluminum bridge to the Middle East."

Facing floor-to-ceiling maps of the gulf region, a crisis team works around the clock to coordinate the movement of troops and equipment. "You've got to keep cool when everybody around you is losing his head," said Brig. Gen. James L. Cole Jr., operations deputy for the Military Airlift Command. "A lot of people are calling, saying they need those planes now."

The massive airlift operation has strained Saudi airfield capacity, and Defense Secretary Richard B. Cheney spent much of his four-day, six-nation tour of gulf states this week discussing the use of other nations' airfields to relieve the Saudi burden. Cheney secured aircraft staging rights in the United Arab Emirates, Bahrain and Oman. The Air Force has positioned squadrons of C-130 transports in those countries and at some remote Saudi bases to ferry equipment that is brought across the Atlantic by

larger C-141 and mammoth C-5

transports. "This is absolutely the most challenging scenario," one aircraft planner said of the Saudi deployment. "You couldn't ask for a worse place if you had to pick one."

The transportation in effect for Desert Shield is the product of a 12-year effort to overhaul the way the military moves itself. During a 1978 exercise dubbed Nifty Nugget, the Pentagon recognized "serious problems in our nation's ability to mobilize and deploy forces on a large scale," as a Defense Department pamphlet put it. But not until 1987 was the U.S. Transportation Command activated to coordinate efforts of the Navy, Air Force and other agencies.

Although virtually all of the soldiers dispatched on Desert Shield have flown to the gulf, 95 percent of their equipment and supplies is going by sea. The ships in use include 13 "maritime prepositioned ships"; eight "fast sealift" ships, which can travel at 33 knots; 13 "afloat prepositioned" ships, most of which were already in the Indian Ocean, stocked with ammunition, medical supplies, and other cargo; and 38 cargo ships activated from the "ready reserve fleet," a sort of 96-ship navy-in-waiting used in emergencies.

As part of the complex choreography, for example, the maritime prepositioned ships were moved to "marry up" with the arriving 7th Marine Expeditionary Brigade of about 16,000 troops, and the fast sealift fleet is expected to arrive in Saudi Arabia early next week carrying the 24th Mechanized Infantry Division and its M-1 tanks from Savannah, Ga.

The military is also drawing on the Civil Reserve Air Fleet (CRAF), an organization in place since 1951 to bolster military aircraft capabilities. Johnson, head of the Transportation Command, has activated CRAF 1, which has permitted him to requisition 17 civilian passenger planes and 21 cargo planes for use in Desert Shield.

The Air Transport Association, which represents major airlines, said yesterday that it knew of no canceled flights because of the CRAF callup. But it said that some minor dislocation is likely among passenger carriers, such as substitution of different types of planes on some routes. Cargo carriers have no problem, however, because this is a slack time of year for freight shipments, an association spokesman added.

That could change if the secretary of defense invokes CRAF 2, Johnson said, although such a move is not anticipated "at this time." Under CRAF 2, the military would requisition 79 civilian passenger planes and 108 cargo aircraft. Under CRAF 3, which can be invoked only during a national emergency, the military fleet would expand to 258 passenger planes, 217 cargo planes and 31 Boeing 767s, which would be used for medical evacuation.

The nation's surface transportation system of trucks and railroads "has not been challenged" by Desert Shield, Johnson said. Even in an "all-out war," military needs would take only 2 percent of the nation's trucking capacity, he added.

Likewise, Saudi port facilities are not likely to be overtaxed by the sealift. Informed sources said it is likely that several dozen more ships in the ready reserve fleet will be activated.

The 30-hour round-trip flight to Saudi Arabia from the United States is expected to stress the Air Force's aging fleet of C-141s. Although 70 percent of the transport planes are flown every day during normal operations, they usually are in the air for only five hours at a time on average. In the past two weeks, the planes have flown an average 11 to 12 hours a day. Some "pretty substantial structural problems" were detected in some C-141s last winter, but the current operation has not seemed to worsen them, Johnson said. The military has lobbied aggressively in recent years for a new transport jet, the C-17.

Staff writer Don Phillips and staff researcher Lucy Shackelford contributed to this report. Molly Moore reported from Saudi Arabia.