U.S. intelligence officials warned yesterday that Iraqi President Saddam Hussein plans to pursue a "scorched earth" strategy in the event of war with the United States and would destroy his country's oil fields, electrical power plants, food storage sites and other facilities while blaming U.S. military forces for the damage.

The officials, briefing reporters at the Pentagon, said they have evidence that Hussein, if he believes his government is about to fall, will try to create a humanitarian crisis that could slow any U.S. invasion and foster international opposition to the war. They also warned that Hussein likely will attempt to release biological or chemical weapons as a last desperate act.

The officials said they cannot predict with certainly which germ or chemical agents Hussein might unleash, or when or where. But they said the likely targets would include not only U.S. forces but also Israel and Kuwait and Iraqi civilians such as Shiite Muslims who have protested Hussein's rule in the past. Iraq has declared it has no stockpiles of chemical or biological weapons.

In preparation for such attacks, the officials said, Iraq has likely shifted some of its stores of anthrax, botulism, ricin and mustard gas nearer to the forces that would employ them -- special Republican Guard units and selected air and missile units located in the central part of the country. To undercut any order that might come from Hussein, the Bush administration has begun warning Iraqi officers that they will be held personally responsible for releasing any weapons of mass destruction.

"Saddam's point of view is, you fight with everything you've got," one official said. "He might use it right away, but he'll certainly use it when he thinks he's about to fall."

Similar U.S. intelligence assessments preceded the Persian Gulf War in 1991 that evicted Iraqi invasion forces from Kuwait, but few proved accurate as U.S. and allied ground troops encountered relatively little Iraqi resistance. It was impossible to independently assess the reliability of yesterday's comments by intelligence officials or the motivation for giving the briefing.

Although the Bush administration has an obvious interest in demonizing Hussein as it lays out a public case for war, a military spokesman attributed the timing of the briefing to a buildup of reporters' requests for an assessment of Iraq's military strength and intentions in the event of war. The intelligence officials declined to specify the evidence to further their case, saying it would compromise sources.

Other officials have argued that, unlike 1991, Hussein will be more willing to fight with nonconventional means because his own government's existence would be at stake.

The Iraqis have been preparing for war since immediately after the Sept. 11, 2001, attacks in New York and Washington, believing they would be a U.S. target, the intelligence officials said. They have accelerated imports of spare parts, moved ammunition closer to troop positions and dug trenches for soldiers and military vehicles. They also have begun placing trucks, concrete barriers and other obstacles on runways at key air bases where U.S. invasion forces might attempt to land.

But instead of planning to engage U.S. troops along Iraq's borders and in the open desert, as they did in the 1991 war, Hussein's commanders intend to use rivers and other natural features as obstacles to any U.S. advance and to set up a layered defense with Baghdad at the center, the officials said.

Iraq's ground and air forces are considerably weaker and smaller than they were in 1991, short on modern equipment, spare parts and training time, the officials said. Morale is low, and so is the Iraqi military's confidence in its ability to battle U.S. troops, they said.

There are about 375,000 Iraqi ground troops, down from more than 1 million a decade ago. Some divisions are manned at only half their authorized levels, and many lack such basic components as reconnaissance units and military police.

"The regular army is not motivated to fight for Saddam, and we don't think they're going to last very long," one official said.

Iraq's six Republican Guard divisions, which are better equipped and trained and number about 90,000 troops, are expected to fight longer. But the U.S. analysts said they have solid evidence that Hussein is concerned about morale even in these elite forces.

The Iraqi air force, with roughly 300 fighter jets, is less than half the size it was in 1991 and is not regarded as a major threat. Iraqi pilots receive on average only 20 to 50 hours of training annually, and when they do fly, "it's basically stick and rudder stuff" rather than serious tactical training, one U.S. official said.

A relatively brighter spot for Iraq's military is its air defense system, which remains largely intact despite years of intermittent strikes by U.S. warplanes patrolling "no-fly" zones in the north and south of the country. The U.S. officials noted that Iraq has kept most of its surveillance radars and antiaircraft missile batteries in the central part of the country, out of reach of U.S. planes.

Additionally, Iraqis have shown considerable resourcefulness in repairing facilities that are damaged by U.S. airstrikes, drawing on spare parts from some former Soviet republics, the officials said. Chinese and Turkish companies have helped Iraq lay a nationwide fiber-optic network, providing communication links among military facilities that are more effective and more difficult for U.S. forces to cut.

"It's really an issue of disruption, not permanent destruction," one official said of the real impact of the U.S. airstrikes.

Iraq's military would be in even worse shape, the official said, if not for large amounts of imported equipment, including trucks, air defense parts and night vision devices.

Many of the imports have been smuggled into the country in violation of international economic sanctions, with Syria serving as a major conduit, the official said. But some have arrived with United Nations approval, such as hundreds of pieces of earth-moving equipment that ended up being converted into missile launchers.