U.S. military officials said that unrelenting allied air strikes have destroyed a third of Saddam Hussein's ground arsenal and rendered useless a vast stock of even more military equipment.

The assessment suggested the allied strategy of forcing Iraq's army to remain pinned down in bunkers had succeeded in ending the threat from many of Iraq's tanks, artillery and chemical weapons.Military officers in Riyadh, Saudi Arabia, told a briefing Thursday night that allied forces had destroyed about one-third of Saddam's military ground equipment, including tanks.

Lt. Gen. Thomas Kelly, director of operations for the Joint Chiefs of Staff, said at the Pentagon that another 15 percent of Iraq's tanks would be grounded if a land war ensued because they lack essential parts from bases in Iraq that have been destroyed.

The figure, if accurate, would bring to nearly 50 percent the number of tanks essentially taken out of commission. At the beginning of the war, Iraq had 4,280 tanks, Pentagon officials said Thursday.

Kelly also suggested that many of Iraq's estimated 5,000 chemical warheads may likewise be useless because, he said, the poisons "tend to degrade over time, the particular stuff that he's using."

He added, "So, while there's probably a threat from that, it's nowhere near as significant as it was at the outset."

The battlefield assessment led Kelly to conclude: "I would say (Saddam's) military position is precarious."

Allied forces have continued to run 2,400 to 2,900 air sorties a day, many of which appear increasingly aimed at ground targets to weaken Saddam's military arsenal and minimize casualties to allied troops if a land campaign is ordered.

In addition to the 1,300 of 4,280 Iraqi tanks destroyed, the allies have reported destroying more than 800 of 2,800 armored personnel carriers and more than 1,100 artillery pieces in Kuwait and southern Iraq, he said.

Debriefings from some of the more than 1,200 enemy prisoners of war have been "enlightening," Neal said, saying the air strikes seem to be lowering the morale of Iraqi troops.

"The bombing campaign - particularly the 24-hour aspect, where they're not getting any sleep, no rest - psychologically it's affecting them," he said. "But just as importantly, they're suffering casualties, both in equipment and men."