It was, the Honduran chief of staff said, a historic event.

The defense ministers of Honduras, El Salvador and the United States stood under a thatched-roof shelter on the dusty coastal plain as 1,080 Salvadoran soldiers baked slowly at attention before them.

The first class of Salvadoran recruits was graduating from a Green Beret training camp built by the United States in Honduras. With a ragged Honduran band struggling gamely to be heard despite the beating of U.S. helicopter blades just outside the compound, the young men of the Arce Battalion were being sent off "to defend democracy and freedom in your own homeland," as Defense Secretary Caspar W. Weinberger told the sweating formation of troops.

Weinberger and his Salvadoran counterpart, in a dark green uniform and mirrored sunglasses, exchanged plaques, as did the Hondurans with the Salvadorans and the North Americans with the Hondurans.

The three military leaders praised each other's nations and urged further cooperation against what Honduran Gen. Gustavo Alvarez called the "Marxist fanatics" of the region. Then they passed around cold Coca-Colas and, with helicopters swirling dust into the hot air, Weinberger, his party and dozens of reporters departed the isolated camp.

Weinberger spent three days in three Central American countries last week, the highest ranking administration official to visit a region that also has been host to dozens of congressmen in recent months.

"We're going to ride him hard and put him to bed wet," Pentagon officials said before the trip.

Weinberger's schedule included 14 helicopter rides, two formal arrival ceremonies, a Panamanian state dinner--at which he received the National Declaration of the Order of Vasco Nunez de Balboa in the rank of the Grand Cross--and dozens of staged events showing what U.S. and local forces can do, ranging from a "live-fire" demonstration at the U.S. jungle training school in Panama to the impressive booming of the USS New Jersey's 16-inch guns during Weinberger's lunchtime visit at sea.

But the elaborate and tightly scheduled performances seemed in a separate world from the insurgencies shaking the region last week.

The Salvadoran town of San Miguel was still recovering from heavy rebel bombardment when Weinberger reached the country. U.S.-backed guerrillas were bombing facilities in Nicaragua while Weinberger slept in the U.S. ambassador's residence in Honduras Thursday morning.

Weinberger scarcely mentioned those events in his public statements, and they did nothing to disrupt his schedule. Perhaps in the way of all official visits, the secretary arrived optimistic and left optimistic.

Had he seen anything unexpected? Weinberger was asked on the way home. "I was pleasantly surprised at the state of proficiency of the Salvadoran forces," he said.

U.S. Army helicopters carried Weinberger and his entourage from the military airport near San Salvador to the front in San Vicente. The 101st Airborne had flown seven green choppers from Honduras--where they are taking part in extended U.S. military maneuvers--to help support the secretary's visit. The Salvadoran forces own 83 aircraft, but they have only 50 pilots and nothing as advanced as the UH60 Blackhawks that ferried the secretary around the countryside.

From above, El Salvador is a beautiful country, red tile roofs standing out against dozens of shades of green in the lush hills. It is the most densely populated country in Central America, and the neatly planted fields lap like waves up every hillside to take advantage of any arable land.

The helicopters circled twice over San Vicente, casting shadows over the white stucco homes and the people staring up from every street. The Blackhawks finally settled into a scruffy soccer field guarded by Salvadoran soldiers with machine guns, curiously looking in toward the secretary instead of out toward wherever the threat might be.

More soldiers stood at every corner as the secretary's motorcade of jeeps and vans bumped through the provincial capital. In the stone courtyard of the headquarters of the Salvadoran 5th Infantry Battalion, Los Pumas de San Vicente, another military band was at work.

Assorted wood-backed dining room chairs and two red leather barber's chairs were lined up in the briefing room. While Weinberger chatted with Gen. Carlos Eugenio Vides Casanova, minister of defense and public security, a U.S. adviser told reporters why San Salvador does not remind him of Vietnam.

"Their experience with democracy" distinguishes them from the Vietnamese, he said. "Maybe it's a little skewed from our point of view, but at least it's rooted here."

In addition, the Army officer said his role is strictly one of training; unlike in Vietnam, Americans never go into combat. Although the Salvadorans are progressing well, he said, that restriction makes his teaching job more difficult.

"That's a real frustration," he said. "We're very much limited in what we're able to do."

Col. Rinaldo Golcher, commander of the pacification program in San Vicente, stood before a map to brief Weinberger.

"We are operating 24 hours a day," Golcher said in Spanish, "not 9 to 5, Monday to Friday, as many people in the United States claim we are."

But Golcher said his army's progress is limited because it is short of soldiers, helicopters, batteries, weapons, ammunition and clothing for bad weather. Weinberger heard the same direct or implied request for more aid at every stop of his trip, and later he said he he found the requests compelling.

"Just a little bit more in terms of military assistance or economic assistance can make an enormous difference," he said.

As the band struck up again, the convoy moved out of the courtyard to a refugee camp a few blocks away. San Vicente's urban population has swelled from 40,000 to more than 55,000 because of fighting in the hinterland, according to a local army official, and many peasants have lived for two or three years in the camp's mud-walled, tin-roofed shacks.

A few women washed babies in tin tubs or cooked over smoky wood fires as Weinberger and his entourage swept through the camp with briefcases, television cameras and microphones, hundreds of little children running along behind. Weinberger expressed his sympathy to an assembled group of women and children and said he hopes they can return home soon.

Before re-boarding his helicopter, Weinberger inspected recruits being trained by U.S. soldiers. As the four-star general of the U.S. Southern Command and other officials and reporters crowded around, Weinberger chatted with three U.S. trainers.

"The commitment is there, but the training time is too short," one said. The soldiers, some of them 15 and 16 years old, are receiving five or six weeks' training instead of the needed 12 weeks, U.S. officials say, and sometimes their training is interrupted to respond to a crisis in another area.

"It's fine work you're doing," Weinberger said, without responding directly to the comment about training time. "I'm glad to hear you say the motivation is good."

As Weinberger moved away, another trainer gathered his courage to say, "Give our regards to the president." Then once again the helicopters swirled up the dust.

Another helicopter ride brought Weinberger to a military base in San Juan Opico, where the leader of the U.S. medical team in El Salvador explained why U.S. aid is needed in developing a system to care for wounded soldiers.

"The sicker they are, the longer it takes to get treated," Col. Hernan Morales said. "There is no medical logistics. There are no professional administrators in the system. The result is that although care in the military hospital is good, medical care elsewhere is poor."

One-third of all wounded soldiers die, Morales said, whereas the proportion should be one in 10. Wounded men wait 12 hours for evacuation, frequently bleeding to death, and then wait another 12 hours for treatment. Of about 6,000 soldiers injured last year, only 1,896 made it to the country's one military hospital--and only three of those died, indicating that the more serious cases never make it that far.

There was no discussion of problems in the civilian medical system, which has been plagued by a shortage of funds and doctors since the Salvadoran military closed and occupied the National Medical School three years ago. But Morales stressed the need for more medical officers and pleaded for four helicopters for medical evacuation.

Without responding directly, Weinberger congratulated the medical team that President Reagan sent to the country last spring.

"You're doing very valuable work," he said. "I can't think of anything more important."

Several mock patients stretched out on the red tile floor as medics gave Weinberger, and the TV crews trailing him, a demonstration of bandaging, attaching splints and hooking up intravenous tubes. A scrawny dog wandered among them.

In Comayagua, Honduras, Weinberger toured a very different medical operation. There 250 American medical experts and six medical evacuation helicopters have moved in for six months or more of joint military maneuvers with the Honduran armed forces. The troops have inflated four Quonset-shaped bubbles to house their hospital and laboratory, and when Weinberger arrived they were still digging trenches, laying paths and preparing to raise a shower tent and a mess tent so they could move away from C rations three times a day.

Their operation was dwarfed by the entire maneuvers headquarters taking shape around them. Acres of red dust and green canvas lay in a valley between two Honduran mountain ridges as 1,500 troops readied their base for the fall and winter.

On a camp bulletin board a notice warned soldiers to behave politely when they visit the capital of Tegucigalpa (dubbed "Tegoose" by U.S. forces) or other Honduran towns. Many soldiers seemed pleasantly surprised by the cool nights in the Honduran mountains and the quick way the tent city has been organized.

"It's something to do," said Sgt. Bruce Henry.

On the terrace of the Maya Hotel, reporters and U.S. military officials breakfasted in the cool Thursday morning air. The hotel has had few vacancies since the United States announced its extended military exercises, and the veteran reporters discussed, again, whether Central America is or is not like Vietnam.

Early in the morning the BBC had reported an explosion at Managua airport in Nicaragua, for which antigovernment guerrillas later claimed responsibility. A U.S. Army colonel involved with the exer- cises suggested the leftist government in Nicaragua should not be surprised.

"Maybe it'll show them they have to moderate their policies," he said. "If they're going to export terrorism and oppress their own people, maybe they have to expect something in return."