Iraq's largely hidden air force has managed to repair up to 20 percent of bombed runways within 24 hours, presenting U.S. commanders with a "target that moves every day and changes," Pentagon officials say.

Meanwhile, the officials said, they expect to take advantage of clear skies over Iraq after days of heavy clouds to assess the damage allied air strikes have inflicted so far.Officials said that while commanders are frustrated that poor weather conditions have made complete damage assessment impossible to this point, Defense Secretary Dick Cheney and Gen. Colin Powell, chairman of the Joint Chiefs of Staff, would have "some graphic stuff" to show at a news briefing Wednesday.

In seven days of war and more than 10,000 air missions, U.S. and allied warplanes have struck most Iraqi air bases with little or no opposition from Saddam Hussein's air force.

But Army Lt. Gen. Thomas Kelly told reporters Tuesday that while runways, railroads and pipelines can be hard hit, they also can be repaired.

"We know there are cases where we bombed runways, they have repaired the runways and been back up operating within 24 hours," said Kelly, director of operations for the Pentagon's joint military staff.

He said the number of repaired Iraqi military runways ranges from 15 percent to 20 percent.

"We've seen airfields go down and come back up," he said. "They are out trying to repair a lot of things. . . . Remember, they still have over a million people under arms and they have capabilities."

Navy Capt. David L. Herrington, the Defense Department's director for current intelligence, noted that the speed with which a runway can be repaired depends on the level of damage it has sustained.

"But it's a target that moves every day and changes," Herrington said.

Kelly said that while it is true airfields can be repaired rather quickly, Iraq's warplanes are not using many of them because "they're not electing to engage in aerial combat."

Kelly dismissed speculation that Saddam is holding back his air force for a massive surprise attack on the U.S. and coalition allies attempting to force him to remove his 545,000-man army from Kuwait.

"That does not seem to make an awful lot of sense since he's being attritted (weakened) while he's doing all this waiting," Kelly said.

"I can't crawl into his head and tell you what his plans are, but . . . we don't expect any difficulty in maintaining a level of effort against him," the general said. "We're not going to punch ourselves out."

Kelly said that while Iraqi forces have started fires in some oil fields in Kuwait, blowing up oil wells and storage tanks, their actions have had no effect on military operations.

But he said those operations could be affected if all the oil fields were torched, creating "a great pall of smoke," and "if we elected to go where those oil field fires were occurring."

"He (Saddam) tries something, you try something," Kelly said. "We would look for another way to do the job. We're confident we can do that."