In a high-technology war of pinpoint bombing and missile fratricide, the U.S. and allied air campaign against Iraq has been hindered by the oldest obstacle to warfare: the weather.

According to U.S. military officials, heavy clouds over Iraq have sporadically obscured bombing targets and prevented accurate photographic assessments of damage after the raid. Although some bombers and reconnaissance planes are equipped with sophisticated electronic devices to cut through the mist, many American pilots find that the most important fog of war is fog.

"If I had to say something bad, I'd say I'd wish the weather would be a little bit nicer right now," Gen. H. Norman Schwarzkopf, commander of U.S. forces in the Persian Gulf, said yesterday on NBC's "Meet the Press."

A spokesman for the Pentagon's Air Weather Service reported scattered rain and clouds over Iraq the past 24 hours, a pattern that private meteorologists -- on the basis of satellite photos -- predict will persist in coming days.

At a briefing Saturday at U.S. Central Command headquarters in Riyadh, Saudi Arabia, Marine Maj. Gen. Robert Johnson said cloud cover has prevented U.S. forces from fully evaluating the damage they think they inflicted on Scud missile launchers used by Iraqi President Saddam Hussein to attack Israel and allied troops in Saudi Arabia.

Johnson, chief of staff of the Central Command, also suggested that bad weather was the reason for some U.S. pilots returning to base without having fired their weapons or dropped their bombs.

"I couldn't talk in percentages," Johnson told pool reporters. "But clearly it does degrade somewhat our ability to fire on targets and certainly to be able to see whatever battle damage that you've been able to inflict on those targets."

Johnson insisted, however, that because of sophisticated technology, cloud cover has "done very little to really slow down our game plan with this air campaign."

According to Pentagon spokesmen, most U.S. fighters and bombers in Operation Desert Storm have the capability to fly in rain and fog. But few aircraft have the ability to precisely target their prey in inclement weather. They fix their crosshair sights by laser beams, which cannot penetrate cloud cover, experts said.

When clouds turned distant objects into indistinguishable radar blobs, U.S. pilots said they abstained from dropping their bombs on targets near population centers.

Retired Gen. John A. Wickham, a former Army chief of staff, said cautious U.S. military strategists restricted bombing during bad weather. Pilots would have to fly below the clouds to identify targets and would be exposed to greater risk from antiaircraft weapons and missiles.

"The operational rule for air crews is to minimize risk to themselves," Wickham said. "They can just wait and strike their target tomorrow or the next day."

One notable exception from the problem in the gulf is the B-52 bomber, workhorse of the Vietnam War, which uses navigation to pinpoint its target. Flying over the bombing site, computers determine the precise moment to release the load.

Bad weather has literally left U.S. reconnaissance missions in the dark, unable to determine the effect of bombing missions, military officials said. Without such "bomb damage assessment," aircraft must revisit key sites to decide whether they should be hit again.

Even the most advanced photographic equipment cannot penetrate clouds, experts said. Nor can most satellites. But as Schwarzkopf said yesterday on ABC's "This Week With David Brinkley," the military has "a lot of other techniques that can also come up with results."

He declined to be specific but, according to one expert, he may have been referring to certain satellites that can detect electronic signals and note whether they are still emitted after a bombing raid.

"Yes, I'd like to have perfect weather," Schwarzkopf said. "But we don't have it. But we don't necessarily have to have it."

Staff writers R. Jeffrey Smith in Washington and Guy Gugliotta in Saudi Arabia contributed to this report.