CRISIS IN THE PERSIAN GULF : U.S. Military Plans Preemptive Strikes on Iraq Missile Sites : Strategy: In the event of an impending attack, early raids could protect American forces, Saudi oil fields.

U.S. military commanders, faced with shortcomings in their sophisticated air defenses against Iraqi missiles, plan to launch preemptive strikes on enemy launch pads at the first sign of an impending attack.

The strategy, spelled out by commanders and senior military officials in Washington and Saudi Arabia, is designed to allow the U.S. military to protect not only American troops and bases but some of the Saudi kingdom’s most vulnerable economic targets as well.

And with the state-of-the-art Patriot anti-missile missiles still in short supply here, officials say they cannot afford to wait to hit Iraqi missiles in mid-flight. The lone unit deployed here so far can provide batteries to protect only eight strategic sites.

U.S. commanders say that they believe early warning photos from reconnaissance satellites would give them at least eight hours’ warning if Baghdad were to launch a missile attack.

The Iraqis probably would use Scuds, Soviet-made medium-range missiles, although officials also fear that Iraq could try to sneak its French- and Soviet-made combat planes into Saudi Arabia to deliver poison gas.

They say they also are refining plans to defend Saudi oil fields and other commercially vital installations, which they say are especially vulnerable to attack by missiles containing poison gas. Currently, many of these facilities are virtually undefended.

“There are some crucial assets in this country which we are in a position to defend,” said Lt. Col. Lee Neel, commander of the Texas-based 2nd Battalion of the 7th Artillery Brigade.

The Army, with many of its units delayed in arriving because of logistics snags, currently is only halfway through its scheduled deployment of the Patriot missiles.

But even as substantial additions to the force arrived this weekend, U.S. military officers conceded that at least some of the missiles that Iraq might fire at targets in Saudi Arabia almost certainly would elude the Patriots, even if the United States had adequate numbers of them in place.

Iraq is said to have more than 200 Scud missiles, along with hundreds of other such weapons.

Iraq’s information minister, Latif Jasim, inspired new jitters Thursday, telling visiting Jordanian reporters that in a war, Iraq would destroy all oil fields in the Persian Gulf.

He also hinted strongly that Baghdad would make heavy use of chemical weapons in any such situation. “Iraq’s strategic plan if it is attacked militarily is to . . . use all weapons at its disposal,” he said.

U.S. analysts in Washington have noted a step-up in Iraqi activity recently that suggests Baghdad has prepared at least some of its launching pads for surface-to-surface missiles such as the Scud.

Since the Scud is notoriously inaccurate, U.S. officials say, the Iraqis are unlikely to succeed in using it to disable Saudi oil facilities. During Iraq’s eight-year war with Iran, it failed to shut down the Iranian oil terminal at Kharg Island, despite repeated bombings.

At the same time, U.S. analysts said, a missile needn’t score a direct hit to disable an oil installation. Just one or two lucky hits could disable facilities and cause economic havoc by spreading terror among foreign laborers who keep the facilities working.

Hundreds of American employees of Aramco, Saudi Arabia’s national oil company, failed to return for work recently after summer vacations, underlining the potential impact that such chemical weapons fears could have on the Saudi economy.

For now, Saudi Arabia has sought to offer hundreds of thousands of its subjects and guest workers the same chemical weapons protection that the U.S. military has.

But the gradual arrival of such equipment, as well as the civilians’ lack of training in using it, is likely to make such efforts largely ineffective in a chemical attack, should one occur soon.

U.S. officials said that Iraq’s recent focus on industrial targets is partly a response to the fact that U.S. and Arab military forces are growing increasingly resistant to such attacks--because of the Patriots, protective gear and the openness of the desert, where nerve gas disperses quickly.

Meanwhile, U.S. military officials have fretted over the devastating effect that even one or two missiles or aircraft that managed to get through--known as “leakers” in military parlance--could have on military and civilian populations.

“The leaker is the concern because he could have a chemical weapon and try to get in at low level,” said Col. Thomas F. Bliss, the commander of an American wing of E-3 Airborne Warning and Control System planes deployed in Saudi Arabia.

“We anticipate that any one of those targets (Iraqi warplanes tracked by the AWACS) could make a dash for the border at any time,” he added.

Those who operate the Patriot missiles, which are the U.S. military’s main line of defense against Scud-borne chemical weapons, warned that “leakers” are certain to seep through the Patriots’ protective shield.

“We’ve got to think about one hitting us,” Neel said recently. “The whole country where our soldiers are is high-threat,” he added.

Jehl reported from Saudi Arabia and Healy from Washington.