Is Washington inching toward military role in El Salvador?

The possibility of some sort of US military intervention to bolster the sagging fortunes of Salvadoran President Jose Napoleon Duarte and his government seems increasingly likely.

Just what form it would take remains unclear.

What is not in doubt is the Reagan administration's apparent determination not to abandon that beleaguered Latin American government.

Over the weekend Washington and other hemisphere capitals were abuzz with reports and rumors of likely new US actions to help prop up the Salvadoran government.

Fresh military equipment was already on the way. Among this new hardware were six Huey helicopters to replace those destroyed or damaged in a guerrilla raid on El Salvador's major air base two weeks ago. As much as $55 million worth of arms and ammunition is to be sent within the next few months.

But this is only the start. The Reagan administration calculates that President Duarte and his embattled government will need much more assistance, perhaps including US troops.

Ths Reagan administration, however, is caught in a dilemma: Although feeling that the Duarte government needs substantial new support - and needs it now - administration planners know that a US troop presence in El Salvador would call down on them tremendous opposition both at home and abroad.

Unless it wants to face that sort of wrath, reminiscent of the struggle faced in the mid-1960s by the Johnson administration on Vietnam, Reagan administration options on El Salvador are limited.

The administration is also worried about the effect of an increased US role in El Salvador on US relations with the Soviet Union. Certainly a US troop presence there would make it harder for the US to continue pressing the Soviets over their intervention in Afghanistan or calling attention to future Soviet actions in Poland's continuing internal crisis.

At the same time, Washington is becoming more and more agitated about Soviet and Cuban arms, which it believes is what is helping an outnumbered guerrilla army take on the Salvadoran Army so successfully.

Meanwhile, according to an NBC report, administration officials reported Feb. 6 that President Reagan plans to take economic measures against Cuba because of what he deems to be Cuba's support of leftist guerrilla movements in El Salvador.

There are also persistent reports, not denied in any quarter, that the handful of US military advisers in El Salvador has already been bolstered by the arrival of several Argentine Army officers - specialists in guerrilla warfare - and that more may be on the way. There were even reports that Argentina was supplying training and logistical support to opponents of Nicaragua's Sandinista government.

Whether Argentines are on the scene in Central America is unclear. But it is known that several Salvadoran military men recently went to Argentina to confer with their Argentine counterparts.

An Argentine role in El Salvador would be unique. If it came about, it would be the first time that this southern nation has ever gotten itself involved in such an affair so far from its borders. Some observers worry that it could lead to an escalation of the Salvadoran conflict. But an Argentine role would take a bit of the onus off the heavy dependence of the Salvadorans on the US.

In Washington there is a sense of urgency, almost desperation, about El Salvador. Last week both Secretary of State Alexander M. Haig Jr. and Assistant Secretary of State for Inter-American Affairs Thomas O. Enders made this clear.

Mr. Enders, testifying in Congress, said flatly that ''the decisive battle for Central America is under way in El Salvador,'' adding that to withhold or delay US aid ''would be to abandon El Salvador.'' Other spokesmen said the US ''would not do that.''

Were these statements preparing the US public for an increased US role? Perhaps.

But as the debate over the escalating US role intensified, so did the persistent issue of human rights in El Salvador - a subject that has led many to question whether the Duarte government merits any increased US aid.