The Reagan administration is at best having spotty success in trying to encourage policy changes in three turbulent Central American countries - Nicaragua, El Salvador, and Guatemala.
At first glance, the administration would appear to hold considerable leverage over each of the three nations. But each has shown, in its own way, considerable resistance to change, based in part on nationalistic reactions against the colossus to the north.
In El Salvador, where there has been a resurgence of the notorious death squads, even a threat to cut off US aid is likely to be ignored, according to one senior administration official.
In left-leaning Nicaragua, administration officials say, pressure from Washington is working to a degree. But the officials contend that Nicaragua has yet to respond adequately to the US call for a halt to Nicaraguan support for the guerrillas fighting in El Salvador.
The administration's decision to reject a request for a visa from Tomas Borge , Nicaragua's interior minister, is one more sign of American displeasure with Nicaragua. Following a State Department announcement of the rejection on Tuesday , Mr. Borge asserted that President Reagan himself had denied the visa in the hope that, because Nicaragua had shown flexibility, it would ''make even more concessions in the future.''
According to a press report from Nicaragua, Mr. Borge said that it would be a ''very serious mistake'' for the administration to regard recent peace overtures and other conciliatory moves made by Nicaragua as a sign that pressure on the Nicaraguan government from US-backed rebels was succeeding.
When it comes to El Salvador, Reagan administration officials say that more military training for the Salvadorean armed forces and next year's presidential election in the United States may improve the situation. But US pressure has not worked so far in curbing the right-wing death squads, some of which appear to be linked with elements of the US-supported Salvadorean government, Army, and security forces.
On the same day that it announced it was denying a visa to Tomas Borge, the State Department disclosed that it was turning down a separate travel request from Roberto d'Aubuisson, the president of El Salvador's Constituent Assembly. Although they will not say so publicly and say they could not prove it in a court of law, some US officials are convinced that d'Aubuisson has links with death squads. This is certainly the view of many well-informed Salvadoreans.
D'Aubuisson is expected to run for president of El Salvador in elections to be held in March. His chief opponent is expected to be former President Jose Napoleon Duarte, a Christian Democrat. Christian Democrats and leaders of agrarian unions which they support have been among the targets of the death squads.
Elliott Abrams, US assistant secretary of state for human rights and humanitarian affairs, says that the upsurge in death-squad activity in El Salvador was one of the reasons he visited El Salvador recently, along with Fred C Ikle, undersecretary of defense for policy.
''In an odd way, the death-squad activity could be considered a positive sign , because it may be a sign of desperation on the part of the violent right,'' said Mr. Abrams in an interview. ''They may feel that if they don't terrorize labor leaders and rural leaders and democratic politicians, why, the thing may work. They may actually have an election, a direct election of a civilian president, and any chance of turning the clock back would be gone.
''On the other hand, the expression of this desperation in acts of murder is despicable, and we wanted to convey to the government - both civilian and military elements of it - how strongly we feel that they've got to put a stop to it.''
Is the administration threatening to cut off aid?
''Well, you've got a real problem here, and that is that we have very little credibility, we as a country, and not just the Reagan administration, . . . in the threat to cut aid,'' replied Mr. Abrams. ''They know that we don't want a guerrilla victory.
''I think we're to some degree in the position of the boy who cried wolf about cutting aid off. We have never said, 'If you don't do this or that, we'll cut aid off.' But we have made these points about human rights so often - we, the US government, including the Congress - that I don't think that most Salvadorean political leaders believe that is a current prospect.
''So we've been looking for other ways of persuading them, partly trough the visit of such a high-level Defense Department official. . . .'' said Abrams, referring to Fred Ikle's participation in the trip to El Salvador. ''You try to argue that the reason that they can't get the military and economic aid they would like is these kinds of behavior. You try to argue that this is a particularly important moment, this four-month period before the election when they have got to make sure that it's possible to have a decent campaign, and you try to think of other ways of pressuring them.
''The thing is, we're not talking about the Salvadorean political system,'' said Abrams, referring to the death squads. ''Nor are we talking about the Salvadorean security forces. We're talking about relatively small groups of people who are willing to engage in acts of murder to protect their political and economic interests.''
Abrams advocates increased US training as one means of combatting human rights abuses. He says that the training ought to be extended to the civil defense, National Guard, and other security forces. It is the latter groups, he says, and not the regular Army battalions, which are the main source of abuses.
The assistant secretary of state said that he is concerned about a ''serious erosion'' in the human rights situation in Guatemala. He said that the killing this year of four Guatemalans employed by the US Agency for International Development was of particular concern to the United States. The US Congress responded by cutting off a request for $53.5 million in economic aid to Guatemala for the fiscal year 1984. As a sign of displeasure, US Ambassador Frederick Chapin is not expected to return to Guatemala until after Christmas. The killings of the AID workers has been widely attributed to Guatemalan military and security forces.