"The concept of repression is relative," said Col. Jose Guillermo Garcia, El Salvador's minister of defense and arguably the most powerful individual in a country filled with accounts of massive government repression.

"When there is disorder, you try to put order. The reaction has to be strong," he said.

There is disorder bordering an anarchy here now, a plague of extremist political violence that has been building for months. In such an environment, some here argue, the line between wanton official repression and what might be considered legitimate counterinsurgency or police action is increasingly hard to draw.

One of the greatest failures of the military-civilian coalitions that have attempted to run this country since a coup against a rightist Army general in October has been their inability to convincingly draw any line at all.

More than 3,000 people have been killed in El Salvador since the current government took power. Most of them, according to church and human rights groups, have been killed by people associated with the armed forces or the nominally disbanded semiofficial spy organization called Orden, which means order.

Some government officials argue that it is no longer possible to tell who is doing the killing.

National Guard uniforms have been stolen by guerrillas and many of the murders in villages throughout the country are carried out by men in civilian clothes, government officials say.

Garcia denounces most of the charges against the military as "a classic measure used by subversives to denigrate the armed forces."

The left, including some members of church and human rights groups, exploit every account of government abuses to win the support of the people and foreign governments for revolution.

But one senior Western diplomat here said, "There is no question" that security forces have tortured and killed people.

Members of the Christian Democratic Party, the largest opposition group under previous military governments and a participant in the current government since January, speculate on "a process of controlling" the most conservative and ruthless elements of the Salvadoran military.

One Christian Democratic leader said privately last week that 40 members of the National Guard, one of several uniformed police and military units, are in jail awaiting trial.

Garcia denied this, but added that between 40 and 50 members of the security forces are discharged every month for "lack of discipline."

"But where do these people go with all their training and military experience?" Garcia asked. "It is a problem."

The most conspicuous leaders of the extreme right-wing who have condoned if not directed the assassinations of moderate leftist leaders are former armed forces officers. They were discharged by the ostensibly progressive group of junior officers who led the Oct. 15 coup against Gen. Charles Humberto Romero.

These rightists maintain extensive contact with colleagues still in the military. Maj. Robert D'Aubuisson, an Army intelligence officer cashiered in October who now leads the ultra-conservative Broad National Front, planned a coup last month. He looked for most of his support from officers who went along with the October coup but who no longer expect that the current coalition government will look out for their interests.

D'Aubuisson's coup was designed to remove Col. Arnoldo Adolfo Majano, one of the two officers who led the October overthrow, and Christian Democrat Jose Antonio Morales Ehrlich from the five-member junta. D'Aubuisson has accused Majano of being a communist.

Majano had D'Aubuisson arrested along with several other conspirators including some military officers. But, in a major blow to Majano's power and a prime example of the junta's lack of real control, other armed forces commanders ordered him released.

Simultaneously, the supreme military command was reorganized so that all junta directives would be channeled directly to Garcia through Col. Jaime Abdul Gutierrez, by far the more conservative of the junta's two military members.

At the time, one U.S. diplomat, asked if he thought D'Aubuisson had left the country, replied acidly, "If you ask me, I think he's probably off somewhere having drinks with the high command."

The Christian Democrats have had their own problems with the military. They did not join the original October junta, because in their eagerness to appear liberal its military organizers sought more left-leaning civilians in the social democratic mold.

In January, the junta's original civilian members resigned, charging the military was not keeping its promises to stop repression as deaths in the countryside increased. Most of a group of Christian Democrats recruited for a new junta and Cabinet subsequently resigned from both the government and the party in March for the same reasons and were placed by activists traditionally in the more conservative wing of the party.

The Christian Democrats currently in the government threatened to resign if D'Aubuisson was released. But when he was, they did not.

Earlier this month, eight Christian Democratic mayors were assassinated. The murderers were not identified but were widely believed to have been rightists, possibly members of the armed forces. Again, the Christian Democrats were on the verge of walking out, but again they did not.

"We didn't resign because that is what they [the extreme right] wanted us to do," said one influential Christian Democratic leader. "And besides, the military said 'No, we don't want those people, we don't trust them. We want you.'"

One important reason for the military to keep the Christian Democrats in the government is that the United States has said it will probably withdraw support if they leave.

The Christian Democrats say that lately they have actually strengthened their links with the military. "The communication between Army officers at a high level and us is getting very close," said one. But he added that there is no doubt the military is in firm control of the government.

"People who don't see it that way are making a big mistake."

Still, deep divisions remain within the armed forces, both structurally and ideologically. Although the military has a unified high command, led by Garcia, a basic split remains between the Army and the so-called domestic forces, especially the National Guard.

It was younger officers in the regular Army, led by Majano and Gutierrez, who overthrew Romero, the last in a string of military presidents unbroken for nearly five decades. Their backers believed that through a liberal policy, as well as selective military action, the threat posed to El Salvador by the extreme left could be eradicated. They also hoped that by ridding themselves of the graft-ridden old high command they could preserve the integrity of the country's military institutions.

But the violence from the left has not abated, despite the liberal policies, and many Army officers feel betrayed and cornered. The security forces, meanwhile, have never wholeheartedly accepted the arguments of Majano and Gutierrez.

Most of the worst excesses, although by no means all, attributed to the Salvadoran armed forces are blamed on the National Guard, whose garrisons are dotted throughout the countryside.

Where most of the soldiers in the Army are draftees and their current commanders are young products of the Salvadoran military academy, the rank and file in the National Guard are older career men.

Their structure and functions are modeled on those of Spain's Civil Guard. Most of them have served since the days of the dictatorship when they were given a free hand to keep order and mount domestic military operations in the name of fighting communism. To the extent that it has been made, the effort to reorient the National Guard appears to have been less than successful.

At the end of last month a squad of more than 20 men in National Guard uniforms with complete battle dress and an armored car drove to a government agriculture cooperative with a list of cooperative leaders considered to be subversive. Twelve of the leaders -- the local directors who are supposed to carry out government-mandated reforms -- were killed and the 160 families living there fled in terror.

An indication of the division within the armed forces and the confusion of the Salvadoran people is that 60 of those families have returned to the farm because they have been given protection by the local Army commander, a longtime friend of some of the cooperative leaders.

Some leftists hope that such divisions will help them when the time comes for full-scale revolution. But most observers familiar with the Salvadoran armed forces believe that the military is concerned above all else with its institutional integrity. The leftists expressly want to destroy that.

The fighting continues and even some of the more liberal military officers, seeing fewer and fewer alternatives, feel greater pressure to destroy the left at any cost.

This attitude fits perfectly into the plans of those conservatives both inside and outside the Army who believe in a Pinochetzo -- after the methods of Chile's military dictator, Augusto Pinochet. The arrest or execution of anyone even vaguely suspected of association with the left is the only solution to El Salvador's problems, they believe.

The more the country is destabilized and polarized the greater the support within the military for just such measures.

Garcia insists that the current high command is "not only interested in a military victory," but believes reform is necessary. "We believe that everything is the product of a process . . . We are trying to balance the situation, trying to decide in what form to eradicate violence."

The Carter administration, which has pledged almost $6 million to the Salvadoran military, argues that if the armed forces are given better communications equipment and training they can be better controlled. Having opposed the Romero government for its terrible record on human rights, the United States does not want to find itself in the position of supporting another brutally repressive government.

But after seven months, El Salvador's military still seems at least unable, if in fact it is still or ever was willing, to control the excesses of its troops. Many diplomats here believe failure to do so may mean a victory over the left at the cost of complete failure for U.S. policy in El Salvador.