For a time in the 1980s, El Salvador was the only place U.S. soldiers could see military action, while politicians in Washington quarreled bitterly over just how much action American forces were seeing.

A public ceremony earlier this month honoring U.S. troops who served in El Salvador's lengthy civil war has called fresh attention to the controversial role played by American forces and has opened the way for participants to speak more freely about their once obscured involvement.

Despite numerous indications at the time that U.S. troops assisting Salvadoran government forces against leftist guerrillas were coming under hostile fire -- and shooting back -- U.S. officials repeatedly asserted that American soldiers were not encountering significant hostilities and were not engaging in combat.

To admit otherwise would have given congressional Democrats, already critical of the assistance effort launched by the Reagan administration, further cause to invoke the War Powers Act and possibly curtail the $1.5 million a day sent to help the Salvadoran military rearm and expand.

But pressing now for belated Pentagon recognition of previously unpublicized military exploits, the soldiers and diplomats who ran America's involvement in El Salvador readily acknowledge U.S. advisers routinely encountered hostile fire and even accompanied Salvadoran army commanders and patrols into combat situations.

Officially labeled trainers, U.S. forces in El Salvador did not confine themselves to headquarters barracks and safe training areas but often traveled around the country, stood beside Salvadoran officers during combat actions and roamed with Salvadoran patrols in territory frequented by guerrillas of the Farabundo Marti National Liberation Front (FMLN), according to interviews with U.S. and Salvadoran veterans of the war.

The Americans helped plan offensive engagements, gather intelligence, organize logistics and supervise psychological operations.

Suspecting a deeper and more dangerous involvement than administration officials were willing to admit at the time, congressional Democrats pressed for details. Although Congress received incident reports from El Salvador and often sent delegations to visit, lawmakers and their staffs doubted they were being given the full picture of U.S. activities.

"We knew we were being misled by the official position," recalled former representative Michael Barnes (D-Md.), who headed a House subcommittee that monitored the operation. "A lot of us were receiving information from other channels -- journalists, Salvadorans, disgruntled administration officials -- telling us we were being lied to."

Drawing parallels with America's slide into Vietnam in the 1960s, congressional Democrats warned against growing involvement in another unwinnable war and with a foreign military whose record on human rights was egregious. But the Reagan and Bush administrations pressed their case for preventing communist insurgents from taking control of another Central American country in the aftermath of Nicaragua's fall to leftist Sandinistas.

One of the Democrats' tools for trying to compel greater disclosure of the U.S. role was the War Powers Act. It imposes on the president certain reporting requirements to Congress if U.S. troops are introduced into "hostilities" or "a situation where imminent involvement in hostilities is clearly indicated by the circumstances." Ambiguous Rules

U.S. veterans of the El Salvador campaign still maintain they did not violate rules prohibiting a direct U.S. role in Salvadoran combat situations. But the rules were ambiguous, leaving room, for instance, for U.S. advisers to draft combat plans provided they left the execution to the Salvadoran army, or for U.S. troops to enter combat areas provided they did not intend to fight.

"Participating directly in combat operations meant giving orders to execute, and that was not allowed," said Joseph Stringham, who headed the U.S. military effort in El Salvador in 1983 and 1984 and later retired as a one-star general. "But being an observer in a command post was something else. A fine line there? Sure, but we didn't cross it."

So sensitive were senior U.S. authorities to anything suggesting a combat role for American troops that they repeatedly denied combat-related awards.

Stringham, for instance, remembers the letdown in 1984 when superiors admonished him for nominating a team of soldiers and medics for combat badges after they withstood a guerrilla offensive at San Miguel, eastern El Salvador's principal city. There could be no combat decorations, he was firmly told, for troops not supposed to be in combat.

The next year, the same rationale led military authorities to deny Bronze Stars for five Special Forces members who helped repel a predawn insurgent attack on a Salvadoran garrison at La Union.

And again, two years after that, two Marines who helped fend off a guerrilla assault on a Salvadoran brigade headquarters at Usulutan were refused combat action ribbons. Acknowledging Combat

To open the way for honoring the performance of these and other U.S. troops, Congress initiated legislation last year signed by President Clinton in February effectively acknowledging that U.S. troops in El Salvador were operating in a combat zone. The law granted Armed Forces Expeditionary Medals to U.S. military personnel who served in El Salvador between 1981, when President Ronald Reagan stepped up aid, and 1992, when the fighting ended in a draw and a negotiated peace accord was signed.

Pentagon officials still are deliberating whether to authorize individual combat-related decorations. Even those most critical of the U.S. military effort in El Salvador favor bestowing honors where honors are due.

"It is very important to separate the war from the warrior," said Rep. David E. Bonior (D-Mich.), who chaired the House task force on Latin America in the 1980s and now is minority whip. "It's important to recognize those who serve."

U.S. advisers in El Salvador were assigned to each army brigade and sometimes to battalions and special detachments. Only 55 trainers were supposed to be in the country at any given time, but the cap did not include several dozen others: "MilGroup" members overseeing use of military aid and advising the Salvadoran high command; medical trainers; and "mobile training teams" that rotated through on stints of up to two weeks.

Administration officials played down the danger, denying U.S. forces were encountering "significant hostilities" and insisting U.S. personnel were not in areas that would expose them to hostile fire. But for U.S. forces there, all of El Salvador was a combat zone.

"No place was what you might call safe," said Walt Cargile, a retired Special Forces sergeant major who served off and on in El Salvador between 1982 and 1990. "If you were going out on a training mission, you might get ambushed. That happened to me several times."

Although the level of guerrilla activity varied over the course of the war and depended on the region, U.S. veterans estimate American forces engaged in roughly a half-dozen intense battles a year. Numerous smaller encounters with insurgents were never even reported, they said, in part because doing so might have brought too many questions from superiors and possibly trigger early orders out of El Salvador. Risky Missions

Salvadoran military officers who worked with the Americans remembered the risks some took.

"Some of the advisers were very daring. They would go out on night patrols. They would go on long-range patrols," said retired Gen. Adolfo Blandon, chairman of the Salvadoran Joint Chiefs of Staff from 1983 to 1988.

Blandon recounted one instance in 1983 when a senior U.S. officer asked if he could accompany Blandon to the town of Tenancingo, while fighting was raging between the guerrillas and the army. The troops had retaken a soccer field on one end of town, where Blandon's helicopter was supposed to land.

"But the pilot landed at the wrong field, and as soon as the helicopter landed, the guerrillas started firing," Blandon said. "The helicopter pilot took off, leaving us pinned on the ground. We had to crawl on our stomachs to a nearby rock wall. Of course, when the officers realized what happened, they sent troops and got us out. But that was a very close call, and there were many others."

The Salvadoran army that U.S. forces set out to retrain in the early 1980s had been schooled in classic European warfare, not anti-guerrilla tactics. It was accustomed to large field maneuvers and would shoot indiscriminately.

The Americans taught the Salvadorans to operate in small units, patrol deep in guerrilla-held territory, maneuver at night, use gunships, apply intelligence information and employ psychological operations. U.S. surveillance aircraft, including AC-130 gunships, provided a steady flow of information on guerrilla activities.

U.S. advisers assisted not only in planning attacks but in arranging for medical evacuations, fixing vehicles, even obtaining Catholic priests to convene regular services.

"My job was to work across the spectrum of military activity and assist with just about everything," said Lt. Col. John McMullen, a member of the Army's Special Forces who served in El Salvador in the mid-1980s. "As advisers, we were Mr. Fixits."

Senior Salvadoran officials who served with the Americans said U.S. advisers helped develop the long-range night patrols, known as PRALS, a key factor in infiltrating small groups of soldiers behind guerrilla lines.

"The PRALS were key to taking the war to the FMLN, not just reacting to their attacks," said one former Salvadoran officer. "The Americans often went along on them, and were often in combat under those conditions. Usually, those that worked with those groups were Mexican-Americans, or Cuban, so they did not stand out. But they were there."

The Salvadorans also credit U.S. troops with turning helicopters into a key strategic weapon in the Salvadoran military arsenal. The influx of several dozen Huey 500s and Huey UH-1H helicopters to the Salvadoran air force, used to move troops rapidly and keep them supplied, proved critical to stemming FMLN advances in the mid-1980s. A Score of Casualties At least 21 U.S. service members died in El Salvador, according to a list compiled by McMullen.

"There's no one complete official casualty list," he said. "I put this one together drawing on various sources -- books about the war, newspaper articles, a memorial plaque at the U.S. Embassy in San Salvador. Then I went to the Army and other services to verify the names."

Only one -- Special Forces Staff Sgt. Gregory A. Fronius -- died fighting, when in 1987 the Salvadoran brigade he was advising at El Paraiso came under guerrilla attack. One Navy Seal and four Marines were assassinated in the streets of San Salvador. One Army soldier died when his helicopter was shot out of the sky; two other Army soldiers aboard survived the crash but were executed by guerrillas on the ground. One Marine committed suicide. The rest died in two separate crashes of helicopters on noncombat missions.

At least 35 Purple Hearts were awarded to U.S. service members wounded in El Salvador.

Had Congress and the American public known then all that veterans now freely acknowledge about the U.S. military role in El Salvador, might things have been different?

"It would have changed the terms of the debate," said Rep. George Miller (D-Calif.), a leading critic at the time. "As long as you could keep the fiction alive that troops were not in harm's way, a lot of people who would have asked questions kept silent." Farah reported from San Salvador.