Cost of Mideast Operation Set at Millions a Day : Deployment: Analysts estimate that the U.S. will spend at least $300 million a month, before a single shot is fired, to protect Saudi Arabia.

Deploying U.S. forces to protect Saudi Arabia and its oil will cost the United States at least $300 million a month with not a shot fired, military analysts estimated today.

But if shooting does start, the cost could triple or quadruple in short order, said retired Rear Adm. Gene R. La Rocque, director of the Center for Defense Information, a private research center.

It is not clear how long the U.S. military will be committed, with Defense Secretary Dick Cheney saying this week: “We don’t know how long it will last. We don’t know when it will end.”

U.S. military officials said they cannot give an estimate of the potential cost of the Persian Gulf operation, which the Pentagon has dubbed Operation Desert Shield.

Defense Department officials said the number of troops to be committed to the region includes elements of the 18th, 82nd and 101st airborne divisions and a mechanized infantry division, and the aircraft include two tactical fighter wings.

La Rocque based his $300-million-a-month estimate on the United States sending 50,000 troops and three aircraft carrier groups with fighter planes to the Middle East.

Alexis Cain, research director of the Defense Budget Project, a private study group, put his cost estimate at $1 billion to $3 billion over six months.

“It depends on a number of things--how many go, how long they stay and what they end up doing,” he said. “But if (Iraqi President Saddam) Hussein’s tank armies come across the desert, then the cost will be much more.”

Defense analysts say it is difficult to estimate costs of the Saudi operation, since both the exact makeup of the U.S. contingent and its expected length of stay remain unknown.

But they cited several previous military deployments for comparison.

Defense officials put the cost of operations in the “Tanker War” of 1987--when U.S. warships escorted Kuwaiti tankers through the Persian Gulf--at $3 million a day.

A major incident then involved the guided-missile cruiser Stark, hit by an Exocet missile fired by an Iraqi jet that killed 37 American sailors.