Sandstorms, dust and broiling heat of up to 120 degrees could complicate U.S. military operations in Iraq if an attack is pushed back until late spring because of weapons inspections and deployment delays.

The military says technological advances have made it easier to fight in any weather. But sand and dust clog engines and air filters and grind down helicopter blades. Heat slows down soldiers and forces troops to transport more water.

A summer war wouldn't be impossible to fight, officials insist, but it would pose big challenges.

"We are accustomed to training in extreme weather conditions," said U.S. military spokesman Capt. David Romley, adding that his own Marine unit trained in the California desert where temperatures often top 120 degrees.

In his State of the Union address Tuesday, President Bush vowed to use the "full force and might of the U.S. military" if necessary to disarm Iraq -- a possible sign that war is not far off.

But many world leaders are appealing for more time to let U.N. weapons inspectors verify whether Saddam Hussein still has weapons of mass destruction.

Although tens of thousands of troops are in the Gulf region or en route there, U.S. officials privately say the ground force necessary for a strike on Iraq will not be fully in place for another several weeks.

But the clock is ticking. Temperatures in February and March are still mild, but starting in late spring the deserts of Iraq and Kuwait -- a key launching pad for any future attack -- become inhospitably hot. By June temperatures often exceed 120 degrees.

From April to early June, dry, dusty winds with gusts up to 50 mph are common. They are followed by yet another hot wind -- the shamal -- that sweeps from the north and northwest from mid-June to mid-September.

Dust storms stirred up by these winds can rise to several thousand feet.

Blowing dust and sand in the summer months take a heavy toll on vehicles and aircraft, and can block the use of laser-guided weapons and gun sights.

The danger of exhaustion and dehydration among troops intensifies. The suits worn by soldiers to protect against chemical attacks are cumbersome and can slow down operations.

Yet the suits are a lot lighter now than they were during the first Gulf War 12 years ago.

"It's just another obstacle to overcome, just like mud or rain," Romley said.

Technical improvements mean air filters are less likely to get clogged than they were a decade ago. And distortion in optical systems, including binoculars and sighting optics on tanks, by surface heat waves is less of a problem than a few years ago.

Officials have already made plans to ship in large quantities of drinking water to the Gulf. In the summer, each soldier must drink 1-1 quarts per hour, said Col. Rick Thomas, the chief spokesman for U.S. troops in Kuwait.

"If so directed, we can certainly fight in summer," Thomas told The Associated Press.

The U.S. military employs night-vision technology far superior to Iraq's, experts say, meaning American forces can do much of their fighting at night, when it's cooler. In the run-up to a possible war, a portion of each training drill in the Kuwaiti desert takes place at night.

Though thin air that accompanies hot weather forces fighter jets to take off with smaller bomb loads, fewer clouds and fog during the summer often enable more bombing raids.

The pitfalls of desert warfare were brought home in spectacular fashion by the poor showing by British equipment during exercises with Oman in September and October 2001.

Britain's Challenger-2 tanks lasted just four hours before their air filters became clogged by the fine desert dust. Almost half the tanks had broken down by the end of the exercise. The troops were plagued by melting boot soles, guns that jammed and radios that frequently went on the blink.

"The official version is that all this has been addressed in last few months, precisely because of the possibility that there will be an operation in Iraq during the months of summer," said Jonathan Eyal, the director of studies at the Royal United Services Institute, a British think tank.

"However, I think it's anyone's guess how many of these questions have actually been addressed," he said.

Britain recently announced that it was sending 26,000 troops -- one-quarter of its army -- to the Gulf in anticipation of a possible strike against Iraq.

American troops have been training in Kuwait, Saudi Arabia and other friendly countries in the region to get acclimated. Training at U.S. bases in California, Nevada and Arizona also pushes soldiers and military equipment to their limits in extreme desert heat.

"We're not talking about precluding operations" in the summer, Eyal said. "We're merely talking about making operations more complicated."