In 1991, the United States pounded Iraq with what was billed as the most sophisticated air assault in history. But if Saddam Hussein believes an attack in 1998 would be more of the same, he may soon become painfully aware of a serious miscalculation, military experts say.

While air attacks alone still cannot guarantee destruction of deeply buried or hidden targets, U.S. fighters are now equipped with an array of sophisticated systems and weapons that are far more accurate and deadly than before.The Pentagon has spent about $40 billion a year since 1991 enhancing its arsenal, which now boasts everything from a 5,000-pound "bunker buster" bomb to laser systems that can guide precision assaults on the most highly protected targets.

"We have improved the accuracy of our weapons and have developed more weapons that are capable of digging really deep holes," said Harvey Sapolsky, director of the Security Studies Program at the Massachusetts Institute of Technology.

"Other than blind luck, there will be almost no way Saddam will be able to defend himself."

Recent changes in the Fort Worth-made F-16 fighter are a good example of how the United States has focused on developing weapons that are more accurate than those used against Iraq in 1991.

Most of the F-16s that would be used in Desert Thunder are equipped with the so-called LANTIRN system. It improves the aircraft's ability to navigate at low altitudes and use lasers to guide bombs to a target.

Bob Keighery, director of domestic F-16 business development at Lockheed Martin in Fort Worth, said the Air Force has assigned the F-16 the job of knocking out enemy radar stations and surface-to-air missile sites.

The role, performed in 1991 by the F-4G Wild Weasel, allows the F-16 to use radar-seeking Harm missiles produced by Raytheon TI Systems in Lewisville, Texas.

Raytheon may also see its new Joint Stand-Off Weapon put to the test in Iraq. It is dropped from Navy F-18s at a relatively safe distance from heavily defended targets and uses a highly accurate satellite positioning system to guide its final approach.

The United States also intends to use the latest version of the Tomahawk cruise missile. Since the gulf war, its range has improved from 700 to 1,000 miles and it uses a satellite guidance system to more accurately attack a target.

The new Tomahawk contains a 1,000-pound titanium warhead that can penetrate walls before exploding.