Approaching the majestic San Vicente volcano, the helicopter pilot quickly increased altitude from 3,000 to 5,000 feet. Crossing the Lempa River, which cuts a writhing path through the center of the country, he went up to 7,000 feet.

"I fly high so they can't hit me," Lt. Cesar Ramirez of the Combat Pilot Group said. "They" are the guerrillas locked in civil war with the Salvadoran government. Ramirez said his helicopters had been hit three times by groundfire here.

About an hour after leaving San Salvador, we reached our destination, the tiny town of Perquin, built atop a ridge of hills. Soldiers in the dirt street below waved, and we landed in a dusty lot next to the town cemetery.

"I circled in order to come in by the safe hill," Ramirez explained. "The other one," he said, pointing to a peak about two miles away, "is full of them."

Last August, Perquin was the site of what the guerrillas claim was one of their principal, if temporary, victories in this two-year-old war. As part of a summer offensive, they swooped into the village of 1,200 persons, declared it rebel territory and dared the surrounding military to remove them. A week to 10 days later, they were gone. The Army has since claimed that Perquin, as well as the rest of El Salvador's territory, is under its control.

A Washington Post article Tuesday reported that in the view of diplomatic, military and rebel sources here, as well as by personal observation of this reporter during visits to the countryside, Salvadoran defense forces appeared to have lost control over at least 25 percent of the country. Morazan Province, where Perquin is located, was cited by these sources as a guerrilla stronghold.

El Salvador's defense minister, Jose Guillermo Garcia, during a subsequent meeting with Post editors in Washington, disputed that report, saying that his forces control all of El Salvador. As proof, he agreed to a request that this reporter be given a militarily escorted trip to Perquin, which the foreign press has been unable to reach since the August attack.

After a two-hour wait yesterday at the spic-and-span military academy here, where 370 cadets are being trained as officers, a local two-man television crew and I took off with Ramirez in a four-seat Huey 500 helicopter. Ramirez said that type of aircraft normally was reserved for civilian government use, but that two of his group's helicopters were "down right now."

As Garcia had said, we found the government in control of Perquin. But that hold seems to be a fragile one and, according to our pilot, the local military commander and residents, it does not extend to the surrounding countryside.

Dozens of children scampered ahead of the soldiers who came to greet our helicopter. Chattering and fluttering around the foreign visitor, they were an instant source of information, in contrast to the adults, who vanished inside doorways at an approach or a question.

"The group of guerrillas came here on Aug. 10," the children said, pushing each other back in their eagerness. Garcia had said the siege lasted one week, although the children insisted that the rebels had remained in the town for 10 days.

"They had FALS and G3" rifles, they said. "There were many young ones, but some really old ones, too. There were eight women. Some of them were in uniforms, but most of them wore raggedy clothes like us. We knew some of them, they were from this town."

Whom did you know? I asked. Silence. Worried looks and a few embarrassed giggles. What did they do when they were here? The chatter started again. "They dug trenches. A lot of them slept in the house on the square. They bought corn from the cooperative. They took the guardsmen and kept them in jail. They shouted a lot. They shouted, 'Free people.' " More giggling.

When did they leave? "The day the planes came."

A boy took me to the church square.

"That's the bomb the plane dropped," he whispered. The crater in the middle of the unpaved street measures about six yards across. In the middle of the crater there are four makeshift crosses.

"Two guardsmen and two reservists are buried there. They died in the fighting. Five others were taken prisoner. The guerrillas took them with them when they left."

In front of the cement shell of what was the National Guard command post before the guerrillas destroyed it, five soldiers in camouflage uniforms sat in the afternoon sun. Had there been fighting here lately? "No, only shooting in the hills." At that precise moment, two shots rang out.

Lt. Francisco Orellana sat in the dark, cool adobe house that is the new National Guard command post. The officers here are relieved every 30 days, he said, and he has been here, at the head of 20 disheveled guardsmen, for eight days now. He is soft-spoken, gray-haired and very friendly.

"The loudest shooting was the day I arrived. But they didn't come in," he said. "We are not in a condition to attack the enemy. We have no instructions to that effect, and in any case, there are many more of them than of us . Besides us, there is only the same number of soldiers from the Commando Operation."

The lieutenant looked up with sudden interest.

"Did you drive here? No? A helicopter? How nice. The road to San Francisco Gotera," the only major nearby town, "is open for civilians, of course. There is some commerce coming up that way.

"But the muchachos," the guerrillas, "turn up there. It's we who have problems with them. And of course, the side roads are very dangerous."

Are there many guerrillas? "Of course. Quite a few. In Arambala there are very many. And in Torola they are abundant." These are two nearby villages.

"For the moment, they are around here, in their camps, doing whatever they wish."

The hour granted by Lt. Ramirez, the pilot, was up, and we took off before the sun began to set.

"Do you want me to fly by the hill to see how they shoot at us?" he asked mischievously. I declined. Below, the children waved goodbye.