Because of Saudi Arabia's Islamic austerity, the Persian Gulf conflict likely will be the most drug-free war ever fought by U.S. troops, an expert says.

"It's like one giant Alcoholics Anonymous meeting, with only large amounts of tobacco and coffee readily available," said Ronald K. Siegel, a psychopharmacologist at the University of California, Los Angeles, School of Medicine.Alcohol is prohibited in Saudi Arabia, where most American soldiers are based. A stimulant called khat and local forms of tobacco called jurak and shammah hold little appeal for the troops. U.S. forces lack access to opiates and hashish shipped through Iraq from neighboring countries, Siegel said.

American soldiers "are just not going to be directly around any trafficking area," although the chance they may get hashish and opiates such as heroin and morphine will increase if the war drags on, said Siegel, author of the 1989 book "Intoxication."

"This may be one of the most drug-free wars our soldiers ever fought," he said. "It will be the first major war in which American troops remain sober."

The main theme of Siegel's book is that humans have a basic drive to intoxicate themselves, much as they crave food, water and sex.

"That's why our troops in other countries have always picked up what drugs were around," he said. "Fortunately, there isn't a lot in the Persian Gulf war theater to pick up."

Some Civil War veterans became addicted to morphine used as a painkiller on the wounded. During World War II, methamphetamine or "speed" was given to troops to keep them alert, Siegel said.

In Vietnam, many soldiers developed marijuana dependencies and heroin addictions.

Allied forces trying to oust Iraq from Kuwait "probably will not carry local drug problems back to their countries," Siegel said.

Siegel has studied khat, also known as alqat, a plant grown in Yemen. Millions of people in the Middle East and Africa chew fresh khat leaves for energizing and euphoric effects.

Most users are in the southern part of the country, far from U.S. troops, he said.