Because of an editing error, the rank of Gen. Gordon R. Sullivan, vice chief of staff of the Army, was incorrect in a story about the military reserves yesterday. (Published 8/22/90)

The imminent call-up of tens of thousands of military reservists reflects a policy adopted by the Pentagon during the Vietnam War to ensure broad national participation in future wars, military and civilian experts said yesterday.

Pentagon officials said they expect President Bush to activate Army, Air Force and Navy reservists this week under a federal law that permits him to call up as many as 200,000 troops for as long as six months. Bush is expected to request far fewer reservists at first, but Army sources said that with 40,000 troops expected in Saudi Arabia by next week, demands for reserves to support them here and in the Middle East could quickly climb to more than 80,000 troops.

In the past 20 years, the military has assigned large portions of its requirements, particularly in support duties, to the reserves and National Guard. Roughly 70 percent of the Army's medical, intelligence and logistical support needs, for example, are now handled by the reserves.

The seeds of this policy were planted by former Defense Secretary Melvin Laird and Gen. Creighton Abrams, former Army chief of staff, according to Pentagon officials. Twenty years ago this month, for example, Laird wrote a memo to the service secretaries in which he said that reserves, rather than draftees, would be the main source of emergency manpower for future buildups.

"They wanted to structure the force in such a way that you couldn't go to war without the Guard and reserves. The politicians went along because it would be cheaper," said Lawrence Korb, a former assistant defense secretary who handled Pentagon manpower issues during the Reagan administration. "I think there was more or less a consensus that we had made a mistake in Vietnam by not getting the American people involved earlier, by not activating the reserves."

Rather than calling up the reserves when the Vietnam escalation began in 1965, President Johnson expanded the active duty force through conscription. This avoided the politically incendiary issue of activating the reserves -- which can send waves of alarm through the electorate -- yet also left a large pool of trained soldiers, sailors and airmen largely untapped.

"Weaving the Guard and reserve into the force is a way of tapping national resolve," an Army colonel said yesterday. "When they're activated, you immediately take the issue into the hinterland. Now we're talking about humanizing this crisis in the gulf, bringing it home."

To sustain the forces he has dispatched to the Persian Gulf, Bush appears to have little choice but to issue a call-up order. Under the so-called "total force" concept adopted by the Pentagon in 1973, reserve forces have become integral to any sustained military operation. "We'll need reservists across the board, in all skills," Lt. Gen. Gordon R. Sullivan, vice chief of staff of the Army, said in an interview.

Among the 600,000 men and women in the Army Reserve, for example, are units comprising two-thirds of the Army's water supply units; half the ammunition, fuel handling and chemical decontamination units; two-thirds of Army hospital units; and 87 percent of psychological operations units. Reservists also make up large portions of the military's finance, supply and food capability.

The 573,000 members of the Army and Air national guards tend to occupy more combat roles than the reserves. Half the Army's infantry battalions are Guard units; more than one-third of the Air Force fighter units and two-thirds of the service's combat communications forces belong to the Guard. "We say half of the combat soldiers on the next battlefield will be guardsmen," Lt. Col. James H. Ragan, a Guard spokesman, said yesterday. "The Guard is your hometown department of defense. There's a lot of identity between the Guard units and their local communities."

Although Congress generally has been an enthusiastic supporter of the expanded reserve role -- largely because reserves are much cheaper than full-time active duty forces -- the expected call-up will add considerably to the cost of Operation Desert Shield, since activated reservists earn the same pay as their active brethren. Some members of Congress also have questioned whether the activation will place a disproportionate burden on U.S. military forces.

"We cannot keep Americans in the Iraqi gunsights without a parallel commitment -- and risk -- by Egypt, the Gulf States, Morocco, Turkey and the European nations," Rep. Toby Roth (R-Wis.) advised Defense Secretary Richard B. Cheney in a letter yesterday. Roth recommended postponing a call-up until Americans receive "solid evidence that we are not in this alone."

The reserves profited with the rest of the military from Ronald Reagan's $2 trillion defense buildup. Once the recipient of obsolete, decrepit equipment cast off by the active forces, reserve units began fielding modern M-1 tanks, Bradley Fighting Vehicles and F-15 fighters. "The rising tide lifted all boats," Korb said.

Many reservists are former active duty servicemen and women -- 13 percent of enlisted Air Guard personnel are female -- who remain in uniform part-time because of the pay, benefits, camaraderie or for patriotic reasons, according to Pentagon officials. Some specialists, such as physicians and nurses, are fulfilling reserve obligations in exchange for government-paid schooling.

Unlike the Army Reserve and Guard, which now account for more than half the service's total force, the 153,400 Navy reservists remain a minority in that service, accounting for 21 percent of the total. The reservists form "almost a Navy in microcosm," according to Lt. Cmdr. Peter J. Reynierse, by handling undersea warfare, aircraft carrier wings, combat search and rescue and a variety of other tasks.

Hundreds of National Guardsmen are serving in the gulf forces, either as volunteers or as part of their regular summer duty. For tens of thousands of others awaiting Bush's summons, "Everybody's just standing by holding their breaths," Reynierse added, "waiting to see what's going to shake."