"Already there is war. Make no mistake, already there is war," the spokesmen for El Salvador's revolutionary left announce as they visit world capitals seeking support for their cause.

But it is not quite what they claim. What is now going on in El Salvador is a shadowy, persistent battle of terror and nerves, provocation and reaction, assassination, strikes and massacres played at least in part to the grandstand of world opinion and at the expense of El Salvador's 5 million people.

It is what one observer, a Marxist turned cynical from frequent visits here, calls "the phony war."

It leaves people -- scores of them each day -- just as dead as would a real war.

Although still in its preliminary stages, El Salvador's war has posed deep problems for the country's Central American neighbors. As the situation becomes more polarized, remaining conservative governments in the region, as well as Nicaragua's new leftist rulers, fear that the unheaval will spill over their borders.

Western powers, who support social change here but prefer to see it come in a neater package, fear that they will have to choose between the extremes of right and left and that their own liberalism will be sorely tested as the communist world chooses its own side.

The problem is perhaps most vexing for the United States. As the dominant power in the hemisphere, Washington is newly committed, at least as a major of public policy, to clamping down on its traditional supporters on the right and learning to listen to the complaints of the left.

In order to address these complaints without allowing the takeover of countries in the region by forces it views as hostile to U.S. interests, it is trying to ride the middle road and has invested heavily in promoting the Salvadoran center.

The center now barely exists here, however, and the conflict appears headed to the point where there will be but two sides to choose from.

The U.S.-backed military-civilian government, led by a five-member junta made up of military officers and Christian Democratic Party members, has been unable to bring peace with force or reform since it took over from a rightist Army president in a coup last October.

The left, which thinks it can seize power, is hoping for a popular call to revolution. The right, which thinks it can grab it back, is waiting for a call to order at any cost. For the moment, both appear content with the continuing destruction of Salvadoran society.

To understand the growing nihilism that exists here it is necessary to understand the nature and strategy of each of the opposing sides.

The first thing both will tell you is that El Salvador is not Nicaragua, its Central American neighbor, although there is an inevitable tendency outside this country to draw parallels between the Salvadoran revolution and last year's successful revolt against the dictatorship of Anastasio Somoza. But the similarities are not nearly so striking as the differences.

Once they had seized the initiative, Nicaragua's revolutionary Sandinista National Liberation Front found itself carried forward on a rising wave of hatred for the one man whose family had ruled the country for nearly 50 years.

The peasants and workers, but also the middle class and technocrats -- in fact, virtually the whole society -- joined in the fight against Somoza and the National Guard, Somoza's personal army. Finally, there were two sides: Somoza and everybody else.

But El Salvador for most of its history has been dominated not by one family but by a handful often referred to as "the oligarchy." The nearly interchangable generals who nominally headed the government for nearly five decades were regarded as the mere tools of this tiny, ultraconservative elite, working to preserve a near-feudal economic system with repression and electoral fraud.

The Salvadoran left was able to project the image of fighting the oligarchy. Given the desperate poverty in which most Salvadoran live, and the refusal of the government to institute serious reforms, it was rapidly gaining support.

But on Oct. 15, the situation suddenly became much more complicated. Young military officers, disturbed by the rampant corruption within the high command, intent above all an maintaining the integrity of the armed forces and ostensibly interested in establishing reforms that could avert the increasingly inevitable revolution, seized the government.

Suddenly, there was a three-way conflict. The right opposed the government but continued trying to manipulate it -- both from within, through remaining hard-line military officers the progressives either could not or would not expel, and from without, through privately financed paramilitary forces.

The moderate left and much of the center initially responded to the military invitation to join the new government, but the extreme left quickly denounced it as a continuation of the past with new window-dressing. Violence began to increase dramatically, official repression increased and eventually drove the moderate left out of the government and into an alliance with the extremists.

The military and the allies, remaining within the newly divided Christian Democratic Party -- the traditional civilian opposition under previous military governments -- now have moved into an accord with at least the more moderate factions of the extreme right.

In the meantime, however, it is not at all clear where the Salvadoran people stand. Among peasants and workers there is certainly admiration for the militant left, which in the darkest days of the old dictatorship was the only force that stood up publicly for reform and an end to repression.

But the peasants are well aware that they will bear the brunt of a full-scale revolution, even as they are hearing the burden of the current fighting. The present government already has initiated reforms nearly as extensive as anything the Marxists had earlier promised.

Spokesman for the left say privately that the reforms, especially the redistribution of land, have made many peasants think twice about revolution. But the left is confident that the reforms, given the current violence, will fall. Meanwhile, government repression is continuing, sometimes provoked and often not, and the left counts on that to win the victimized majority of the Salvadoran people to its side.

The middle class, which in Nicaragua finally threw its support to the revolution, has stayed steadfastly on the right in El Salvador. It tends to be extremely conservative in any case, and even those who are not have few hopes that any form of capitalism will be allowed if the revolutionaries triumph.

The more powerful factions of the extreme left have made it absolutely clear that they are fighting against a system, not just against a government.

Related to this is perhaps the worst liability with which the left in El Salvador has saddled itself: a reputation for reckless terrorism. There is a perception, both inside the country and among moderate foreign governments that might otherwise support this revolution as they did Nicaragua's, that the militant left of El Salvador will use any means to win its rather ill-defined ends.

Although Somoza often denounced the Sandinistas as terrorists, few people actually believed that they were. Their own acts tended to give them a positive, even heroic image in the eyes of the Nicaraguan people and the world.

El Salvador's guerrillas, on the other hand, have used kidnaping, assassination and summary execution as some of their main revolutionary tools.

"The reason for the kidnapings is clear," a representative of the Popular Liberation Forces, one of several guerrilla groups, said matter-of-factly. "The war needs to be financed. It's not free. The people are very poor, with much misery. They finance part of this war, but not all. The kidnapings are like a war tax."

In all, the spokesman said, his and the other guerrilla organizations have collected more than $30 million in this way. Several of the victims have died in the process.

As for the numerous incidents in which villages are briefly taken over and suspected informers are shot or, in some cases, killed with machetes, the guerrilla spokesman said: "In taking the villages we establish people's courts before we try to execute anyone. But we don't do this without gathering every bit of evidence proving that they have participated in massacres and murders."

There are many members of the newly formed Revolutionary Democratic Front, a coalition of guerrilla, political, union and popular groups, who do not condone such actions.They are moderate leftists by and large, and many of them participated in the first coalition government set up by the military after the Oct. 15 coup.

But the leftist front is so structured that these people have little voice in the way the war is conducted. When asked, they will say frankly that they do not speak for the guerrillas.

This separation of powers and functions has been a hallmark of the Salvadoran left. For years the leadership of the three major mass organizations -- public coalitions of students, workers and peasants -- said they sympathized with the three main guerrilla groups but were not directly connected with them. Now, although their central coordinating bodies are still separate, there are no pretensions about the mass organizations' being anything other than the powerful public wings of the guerrillas.

There are strong indications that increasing numbers of arms already are flowing to the guerrillas. The sources are still unclear, as is the ratio of arms purchased to arms donated.

But the military balance "is still unfavorable to us," said the spokesman for the Popular Liberation Front. "The government Army and security forces have a high level of technical skills. At this moment, though they've suffered many blows, their firepower is still great.

"At this moment we already have a popular army with a hierarchy of officers, some of some of whom have 10 years of experience," he said. "There are enough for the existing forces" -- believed to be in the neighborhood of 3,000 to 5,000 men and women, compared to a few hundred a year ago -- "but we need more for expansion.

"Basically we have gotten arms from the enemy by capturing them and from the capitalist arms market. We've bought arms from all sides," he said.

There have been some reports that Cuba is supplying arms to the revolutionaries, but these are almost totally unconfirmed and widely denied, although there is evidence that Cubans train Salvadoran guerrillas in Cuba. The most obvious supply line, however, is well defined.

Many of the guerrilla arms captured by the government originated in Venezuela. But they were never intended for El Salvador. They had been sent by the former government of Social Democrat Carlos Andres Perez last year to Nicaragua's Sandinistas. Instead, however, they were apparently cached in Costa Rica, which also supported the Sandinistas and acted as their main supply route.

With more than 200 unguarded landing strips in Costa Rica it is a simple matter to sell and transport these arms, for reasons of profit or ideology or both, to the Salvadoran guerrillas. Earlier this month a Panamanian-registered airplane, which had apparently stopped briefly in Costa Rica, crash-landed in El Salvador. A companion plane landed and rescued the crew, but 22,000 rounds of ammunition were subsequently found on board. There is little doubt that the bullets were intended for the guerrillas, or that other shipments have been delivered.

Although the Costa Rican government publicly supports the current Salvadoran government and the Panamanians are remaining relatively neutral -- they say the plane that crashed was stolen -- a U.S. diplomat here claims that "there is no way this stuff can be coming in without the participation in some way of the Panamanian and Costa Rican governments, and the ultimate chances of peace here depend on the quantity and sophistication of the weapons coming in."

The arms are vital to the next stage of guerrilla activity -- the beginning of the real war. But that is still not the popular insurrection predicted by the left. The strategy calls for local uprisings, combined actions of the regular guerrilla armies and the militias formed by the popular organizations, to secure certain regions of the country and make it impossible for the government to enter them.

This would give the the guerrillas something they have never had before: secure supply lines and permanent training bases.

The guerrillas here do not have the convenience of friendly neighboring countries that the Sandinistas had Guatemala is publicly hostile, and even Nicaragua, although sympathetic, has tried to stay officially out of the conflict.

Already some areas of El Salvador -- Chaletenango, San Vicente, and Morazan, among others -- are close to this stage of guerrilla control. The next step is the revolution itself, but no one is saying how long that will be in coming. It could be a matter of days or months.

The only things that seems certain is that eventually the phony war will become a very real one.