U.S. forces may use a new "e-bomb" during the expected invasion of Iraq as part of a 21st century assault designed to render Saddam Hussein's forces blind, deaf, dumb and incapable of retaliation.

The highly classified bomb creates a brief pulse of microwaves powerful enough to fry computers, blind radar, silence radios, trigger crippling power outages and disable the electronic ignitions in vehicles and aircraft.

"They would be useful against any adversary that is dependent on electronic systems," said Loren Thompson, a defense analyst at the Lexington Institute, a think tank based in Arlington, Va.

In modern warfare, electronics support virtually every weapon more sophisticated than a rifle or hand grenade. For that reason, Air Force scientists have worked for decades on a practical way of producing powerful but brief pulses of microwaves that can incapacitate electronic equipment without damaging buildings or harming people.

Officially, the Pentagon does not acknowledge the weapon's existence. Asked about it at a March 5 Pentagon news conference, Gen. Tommy Franks, head of U.S. Central Command, said: "I can't talk to you about that because I don't know anything about it."

However, military analysts say a number of unclassified documents suggest such a device is ready for the battlefield.

"There's been a lot of discussion behind closed doors in the Pentagon and in the trade press that these things are now being tested," Thompson said.

According to a 2000 report by Air Force Col. Elaine M. Walling, scientists at Kirtland Air Force Base in New Mexico have created microwave sources that generate up to 10 times the amount of energy that Hoover Dam produces in a day.

Such powerful pulses can incapacitate electronic equipment without damaging buildings or harming people, making them an attractive weapon whenever civilian casualties are a concern.

In laboratory tests, microwave pulses can melt silicon chips, pushing their circuits far beyond their capacity to conduct electricity. But on the battlefield, even the most impressive e-bomb's effects rapidly diminish with distance. Although e-bombs' capabilities are classified, military analysts believe their range is a few hundred yards at most.

That relatively short range decreases the odds that hospitals, orphanages and other civilian infrastructure will be affected, unless they are directly adjacent to or networked with military targets.

"I think it is almost always more humane to use this compared to a conventional weapon," Thompson said.

The bombs' effects are also hard to predict, analysts say. The surge of electricity produced by a microwave pulse could go directly to the nearest bank of military supercomputers, or it could just as easily be shunted harmlessly into the ground.

"The effects are hard to focus. The moment the energy is absorbed into wiring or other electrically conductive material, you don't know where it's going to go," Thompson said.

Those uncertainties and others may prevent e-bombs from playing a major role in the anticipated U.S. offensive against Iraq, said Lt. Col. Piers Wood, a military analyst at the defense policy think tank globalsecurity.org.

"There will be a few commanders who will see these and get to try them out," Wood said. "We're not talking about arsenals of these things."

Defense experts are particularly eager to see if e-bombs can reach into deep underground bunkers that could otherwise be neutralized only by tactical nuclear weapons.