RIYADH, SAUDI ARABIA, JAN. 17 (THURSDAY) -- The thunder of jet afterburners shook the ground at air bases around this country in the early morning darkness today as waves of U.S. and allied warplanes launched a massive air attack against Iraq, hitting targets in Baghdad and elsewhere in the country.

Nearly 17 hours after President Saddam Hussein ignored a United Nations deadline for his forces to withdraw from occupied Kuwait, a squadron of F-15E fighter-bombers took off from an air base in central Saudi Arabia at 12:50 a.m. (4:50 p.m. EST), in the first military action of Operation Desert Storm.

"This is history in the making," Col. Ray Davies, 44, from Battlebrook, N.J., told reporters. "We've been waiting here for five months now. Now, we finally got to do what we were sent here to do," he said, as he watched American pilots man their aircraft, taxi down the runway and take off.

Each plane's pilot and weapons officer walked across the concrete in pairs to waiting planes that were armed and ready to go. The jets, heavily loaded with bombs and extra fuel tanks, took off in pairs and faded to red dots as they gained altitude.

"It's like the Dallas Cowboys football team," said Davies, the base chief maintenance officer. "They weren't a real emotional team. That's exactly what it's like with these pilots out here. They know exactly what they've got to do."

At 5:30 a.m., more than four hours after taking off, six F-15Cs of the 1st Tactical Fighter Wing from Langley Air Force Base, Va., returned to an eastern Saudi air base. The 18 other jet fighters in the squadron had not yet completed their missions.

F-15Cs, armed with Sidewinder and Sparrow air-to-air missiles, are designed to clear the skies of enemy fighters so the F-15E bombers can reach their targets unmolested.

Ground crews said none of the first six F-15Cs to land had fired any of their missiles or jettisoned their external fuel tanks, indicating that none of the planes had been involved in any dogfights.

As the steel-gray fighters taxied to a stop on the runway at dawn, ground crews ran out with fuel hoses to perform "hot pit refueling," which allows the planes to return to the skies fully refueled in roughly 15 minutes. The ground crews had practiced the technique hundreds of times.

"Soldiers, sailors, airmen and Marines of United States Central Command," the commander of Desert Storm, Gen. H. Norman Schwarzkopf, told his troops in a message shortly after the attack on Iraq had begun, ". . . you have trained hard for this battle and you are ready.

"During my visits with you, I have seen in your eyes a fire of determination to get this job done quickly so that we may all return to the shores of our great nation.

"My confidence in you is total. Our cause is just! Now you must be the thunder and lightning of Desert Storm. May God be with you, your loved ones at home and our country."

About 20 minutes after the first F-15s took off, U.S. KC-135 refueling planes took off from Riyadh, the Saudi capital. British news reports said Royal Air Force Tornado GR1 fighter-bombers had joined the air assault, and Saudi sources said 150 Saudi F-15s and Tornados also took part.

"Our planes went in. The bombs went down," said a Saudi military spokesman in Dhahran. The first Iraqi targets were Scud surface-to-surface missiles, according to military officials in Dhahran.

A U.S. pilot interviewed by pool reporters said jets over his target, which was not identified, had encountered "a lot of 'triple-A' -- that's anti-aircraft artillery," and possibly one surface-to-air missile. But he said the U.S. planes had been able to attack from a sufficient distance to avoid being severely endangered.

Some reports said five Iraqi Scuds were fired at Saudi Arabia, but the U.S Embassy in Riyadh reported that there was no sign that Iraqi missiles had fallen in Saudi Arabia, and diplomatic sources said that they knew of no Iraqi counterattacks.

However, a small oil storage facility near Khafji was reportedly hit by a short-range missile or artillery shell. According to a Saudi oil industry official and a Western diplomat, the facility -- owned by the Arabian Oil Co -- was burning, but the sources described it as a minor fire.

The oil industry source said there was no other damage to any Saudi oil facility and that crude-oil production was normal today, "as if there were no war."

Air raid sirens sounded in Riyadh and Dhahran, where U.S. military officials ordered reporters to don gas masks and take refuge in bomb shelters. Air raid warnings also sounded in the industrial city of Jubail, on the coast north of Dhahran.

In Dhahran, the air raid sirens sounded after a sudden blackout, news agencies reported.

The hotel staff at the Dhahran International Hotel, some near panic, herded 700 reporters and hotel guests into the hotel basement. Hotel officials struggled to keep order and one security officer shouted, "Sit down or you will be tried!"

Immediately afterward, at 3:50 a.m., a hotel security officer issued a gas "all clear," indicating it was safe to remove gas masks. But he warned the guests: "You should be aware that the early stages of an offensive is the most likely time for an attack" on Dhahran.

Asked about the beginning of the U.S.-led campaign to liberate Kuwait, invaded and occupied by Iraq Aug. 2, the Kuwaiti minister of planning, Suleiman Mutawa, said in a telephone interview from Jiddah: "I feel elated, but still worried because you never know what consequences there are going to be for people all over the place."

The U.N. deadline expired at 8 a.m. Wednesday here (midnight Tuesday EDT) on a bright, cloudless morning, finding U.S. and allied ground troops continuing their movement north toward the Saudi border, unhampered by the rain that bathed the Arabian Desert for the previous two days.

"We're a bunch of racehorses that smell the barn right now," said Army Chief Warrant Officer Ron Moring, 32, an 82nd Airborne Division helicopter pilot. "It's time to quit the pre-game show. We're a lot more serious about what we're doing. There's a little more excitement in the air."

At a briefing in Riyadh Wednesday, U.S. military officials had set the order of battle. Army Lt. Col. Greg Pepin said U.S. troops deployed against Iraq now number 425,000, only 5,000 short of the number deemed necessary by the Pentagon to mount an offensive against more than 500,000 Iraqi troops deployed against them.

The latest figures on U.S. military strength included 320,000 Army and Marine ground troops, six aircraft carrier battle groups and two battleships, Pepin said. In all, he added, Desert Shield has now deployed 1,700 helicopters and 1,800 warplanes in the region.

Also Wednesday, French President Francois Mitterrand committed about 16,000 French troops to any offensive in what until this morning was called Operation Desert Shield. Premier Michel Rocard said the French forces would be placed under U.S. military command, for "predetermined missions" of a specific duration, including "the liberation of Kuwait."

With the French commitment, Pepin said, 16 nations had forces arrayed against Iraq -- more than a half-million troops in all -- and another three nations had committed non-combatant ground forces, such as medical units. Fourteen countries have sent warships to the region, he said, and U.S. Navy sources said the aircraft carrier USS Theodore Roosevelt had passed through the Suez Canal to the Red Sea Tuesday and the aircraft carrier America was in the eastern Mediterranean. With six carrier battle groups now in the region, the Navy had 470 warplanes deployed in the region.

On Wednesday, northbound lanes of Saudi highways remained clogged with caravans of military vehicles carrying everything from main battle tanks to drinking water, an indication that many units were still moving toward forward assault positions.

Rain earlier in the week also retarded preparations somewhat. At one forward supply base, Marines spent a good part of Tuesday and Wednesday emptying trenches and bunkers of water and drying communications gear. The rain briefly turned some dirt roads into muddy swamps, but most areas had dried out by late Wednesday beneath the desert sun.

For many units, the prospect of battle brought a growing sense of urgency to training exercises. Pepin detailed a complicated regimen for almost all ground combat divisions, including live-fire exercises with M1A1 tanks, small arms and artillery, as well as night maneuvers, night obstacle breaching, anti-armor tactics and mine warfare.

At the 82nd Airborne Division Wednesday, soldiers performed "Military Operations in Urban Terrain," checking for booby traps, breaking into artificial buildings and clearing them of enemy soldiers by firing their M-16 rifles into stuffed dummies. When the balloon heads popped, the drills were over.

The 82nd Airborne, one of the few lightly armed units in what promises to be a predominantly heavy-weapons war, will likely be called upon to occupy and secure Kuwait City and clear it of Iraqi troops.

Pepin noted that there had been no military indication that Iraqi President Saddam Hussein intended to take his troops out of Kuwait. "We continue to see Iraq occupying defensive positions, fortifying those positions and not withdrawing," he said.

He also noted, however, that the Iraqis "do have the capability of going on the offensive on short notice." His statement marked the first time in months that a U.S. military spokesman in Saudi Arabia had suggested the possibility of an Iraqi attack.

The U.S. Central Command had consistently portrayed Iraqi soldiers and tanks as a purely defensive force dug into protective bunkers behind a formidable belt of barbed wire, mines, trenches and other obstacles.

Pepin refused to expand on Iraqi intentions, and also ducked questions about the state of readiness of U.S. forces, saying only, "We are prepared to carry out any orders the president {Bush} directs." He said that second-stage, reinforcement deployments announced by Defense Secretary Richard B. Cheney in November "are on schedule."

This left unresolved the issue of whether the Army's VII Corps, consisting of three tank divisions from Germany and Fort Riley, Kan., had had time to organize fully and conduct necessary training before taking their places in the front line.

For the first time in the month that the U.S. Central Command has been giving briefings in Riyadh, Pepin mentioned that VII Corps had been conducting training exercises, and his figures for total troop strength also suggested that virtually all VII Corps personnel had arrived in the region. Still, several military sources have indicated that some VII Corps equipment was still en route to Saudi Arabia by ship.

Rear Adm. William M. Fogarty, commander of the U.S. Middle East Force and the Maritime Intercept Force, said Wednesday that allied ships had sighted 20 floating mines in the Persian Gulf over the last few weeks, but added that he had "no indication" that the mines were deliberately set loose by the Iraqis. He suggested that they had come loose from their moorings along the Kuwaiti coast and had drifted south.

But the early focus of war against Iraq is expected to be a prolonged air offensive, as U.S. and allied warplanes try first to neutralize Iraqi air defenses, then destroy Iraqi planes and finally move to provide close air support to ground forces.

Combined air exercises recently included Operation Fish Barrel, which tested command-and-control procedures for attacking enemy armor. The air forces involved were U.S., Saudi, British and French, as well as the U.S. Army's Cobra and Apache attack helicopters.

Pepin several times mentioned participation by Saudi troops in combined exercises, taking particular notice of about 490 Saudi combat engineers who practiced techniques for breaching "enemy obstacle belts" and mine-clearing. The Saudis have said they will participate on the front lines of any ground assault. Egyptians, Kuwaitis and other gulf state forces are also expected to play a front-line role.

Pepin called special attention to U.S. air warfare preparations, describing several combined exercises by "Joint Air Attack Teams" (JAAT) comprised of troops on the ground and their supporting aircraft: "JAAT . . . {envisions} the operation of attack aircraft from the Air Force, Navy and Marines in conjunction with friendly artillery and attack helicopters such as the Cobra and the Apache engaging multiple targets at the same time at the same location on the battlefield," Pepin said. "JAAT operations enable maximum firepower simultaneously to destroy multiple targets. It's a fantastic capability."

At an air base in central Saudi Arabia, the 53rd Tactical Fighter Wing counted down the final seconds until the Jan. 15 U.N. deadline expired, then gathered in front of one of their F-15C fighters for a group picture.

"We finally broke down the bureaucracy of how to get a picture," laughed squadron commander Lt. Col. Randy Bigum, 41, of Springfield, Va. "Organizing 40 pilots is a contradiction in terms."

Like many Desert Shield soldiers, the pilots regarded Jan. 15 as the opening gun in what they believe will be a quick, brutal -- and successful -- war. "There's not going to be an Iraqi airplane flying after the second day of the war. That's what our whole objective is," said pilot Capt. Mike Miller, 28, an F-15 pilot from Kingsport, Tenn.

Elsewhere, the mood was more somber. At the 82nd Airborne, paratroops wrapped up keepsakes and souvenirs and mailed them home, one less package to carry with them. Others burned their letters so no one could trace the addresses.

U.S. Marines went about their preparations for war in a mood of grim resignation.

"I don't know anyone who doesn't want to go home," Staff Sgt. Allen Bruce, 27, of Riverton, Kan., told his men shortly after a red dawn overcame the nighttime chill.

"You are not the only ones in these holes," he added, referring to the earthen fortifications where Marines at this forwardmost supply depot work and sleep. "You're not the only ones pulling all-nighters. We all are. We're all tired. We're all dirty. We all stink. But that's life in the Magic Kingdom."

Staff writer Molly Moore and correspondents Edward Cody and Caryle Murphy in Saudi Arabia contributed to this report.