Washington — Even before deciding precisely how it will aid El Salvador, the Reagan administration has made a commitment to that nation's defense from which it will not be easy to back away.
That commitment was one of the subjects that President Reagan discussed Feb. 26 in his meeting with Britain's Prime Minister Margaret Thatcher. At a colorful White House welcoming ceremony, Reagan declared that Anglo-American cooperation was "the key" to solving problems in africa and Central America.
"Our challenge today is to ensure that belligerence is not attempted . . . by false perceptions of weakness," the President said.
The administration has chosen El Salvador, a small Central American nation wracked by inequalities and violence, as a key place to reverse any such perceptions and create a new impression of American strength.
"Today, once again, our sense of common purpose and common resolution is being tested," and Mrs. Thatcher, speaking of more than just El Salvador. "It will not be found wanting. We in Britain stand with you. In Britain, you will find a ready response -- an ally valiant, staunch, and true."
In El Salvador, the administration is considering increases in economic and military aid. But the amount of military assistance has been the subject of debate among officials. The Pentagon reportedly has prepared recommendations for sending helicopters, patrol boats, communications equipment, and a small number of military advisers to train Salvadorans.
Senate majority leader Howard H. Baker (R) of Tennessee said after a discussion with President Reagan Feb. 25 that he favors sending as many as 150 military advisers to El Salvador. But the President and other officials repeatedly have denied any intention of going beyond that into a "Vietnam-type" involvement. The show now has 19 military advisers in El Salvador in addition to eight military attaches at the American Embassy there.
In the meantime, the administration is moving ahead elsewhere in the world on other arms and aid decisions:
* plans have been made to give Saudi Arabia most of the supplemental equipment it has requested for the F-15 fighter planes it already has purchased. To offset this, the administration plans to provide Israel with additional F-15s under preferential financing, grant it the right to sell Israel Kifr jets and other equipment with American components to other nations, and possibly work out other benefits yet to be negotiated.
* The monitor has learned that the US also plans to provide the United Arab Emirates (UAE) with new ground-to-air defense systems. A pentagon team recently returned from the Gulf after assessing the UAE's defense needs.
* Debate continues among American officials over requests for help from Afghan insurgent groups. According to some reports, the US has has been aiding the freedom fighters in Afghanistan for some time by helping, among other things , to coordinate the supply of Soviet-made arms by Egypt. But insurgent leaders have complained that they are getting far from enough arms to cope with Soviet tanks and helicopters. One Afghan leader, Ahmed Gailani, currently is visiting the United States.
At some point, the administration also will be expected to reply to requests for help from the UNITA guerrilla forces fighting the marxist government of Angola. The UNITA leader, Jonas Savimbi, is expected to visit Washington within the next few months.
The Carter administration rejected Mr. Savimbi's aid requests during a trip he made to the US last year. A number of black African nations, including oil-producing Nigeria, strongly oppose outside support for Savimbi, in part because of his links with South Africa. But some sources, among them William E. Griffith of the Massachusetts Institute of Technology, say that Savimbi may be getting more significant support from some West European and Middle Eastern nations than from South Africa.
During his election campaign last year, President Reagan spoke in favor of aid to Savimbi. But most of the administration debate that takes place on this delicate subject can be expected to occur behind the scenes.
Debate on El Salvador aid, however, now is in the open and widely reported on , even as it occurs within the administration.
In the US Congress, a number of critics have emerged. One of the most outspoken is Rep. Clarence D. Long (D) of Maryland, who chairs a key House subcommittee and thinks the emphasis should be on economic, not military, aid to El Salvador. But a number of staff specialists in Congress think that given the current mood of the country, congressional support for El Salvador aid package will be widespread -- as long as there is no major setback for the American effort on the ground.
"As long as this works, you'll get support," said one such specialist. "But it it goes badly, you'll hear more and more about 'another Vietnam.'"