Central America

If it is true that the United States can deal with only one world crisis at a time, then what appears to be a momentary hiatus in US policy regarding Central America is understandable. Central America is on a diplomatic middle burner if not a back burner. The Middle East - and particularly Lebanon - occupies center stage. Israeli Prime Minister Yitzhak Shamir is in Washington for talks. President Amin Gemayel of Lebanon arrives Thursday.

But it is precisely because events elsewhere are commanding the political spotlight that the US may now have a vital opportunity - limited as it is - to take those steps absolutely necessary to move events in Central America in a direction that is most conducive to regional stability.

In a sense, the US is already doing just that. Ambassador Thomas Pickering's blunt words in San Salvador late last week could hardly have gone unnoticed by the Salvadorean military and political leadership. El Salvador's government, Mr. Pickering told a group of businessmen, has failed to take proper action against right-wing death squads, despite having lost some US aid as Americans became more and more disenchanted.

Mr. Pickering said what many Americans are now privately thinking these days. In providing military and economic aid to El Salvador - along with a small contingent of advisers - the United States has committed its prestige and authority to shoring up a government that has far to go in winning the hearts and minds of the Salvadorean people. Yet, it is that popular support that more than anything else will be the vital factor in preventing a leftist takeover. If the past few decades have taught any lesson, it is that no amount of aid, or outside military troops for that matter, can long keep a government in power once public support has been lost.

The Reagan administration should use the next month - until the Kissinger commission weighs in with its report - to drive that message home to San Salvador.

There is another side to the Central American equation that also warrants notice. That is a need to stay alert - to listen, if you will - to the possibility of genuine negotiations with Nicaragua. The US says it is willing to negotiate and will do so when Managua comes forth with substantive proposals aimed at ending its backing for El Salvador's guerrilla forces. But is the US serious, wrapped up as it is in a need to ''check'' communist subversion in the region? Recent ''concessions'' from Nicaragua, according to the administration, are ''cosmetic'' and not to be taken seriously.

Evidence from both within and without Managua suggests that the latest offer is more showcase than substantive. Some Cuban troops would be sent home under the proposals. But many, perhaps most, would remain. Salvadorean guerrilla leaders would leave the country. But they would probably be safer elsewhere - in the event of a US invasion. Censorship of La Prensa, the only major antigovernment daily still functioning, is easing. But La Prensa is hardly free and may have to cease publication early in December for lack of government-sanctioned newsprint. And so on.

Managua is feeling pressure from the US-backed contras. The contras could not actually overthrow the Sandinista regime. Even the CIA says that is unlikely. But fighting contras means redirecting resources within Nicaragua away from revolution-building.

Opinion within Central America, and even within the US liberal community, has been shifting somewhat regarding Nicaragua. The more conservative regimes of the region now talk about US intervention to help overthrow the Sandinistas. Within the US, many liberals seem more disposed to see the regime as an interventionist , Marxist-leaning state. Congress, for all its concerns about CIA-backed rebels in the area, has funded the contras well into next year. Such shifts in attitudes give the US some additional time to sort out its long-range relationship with Managua. Such shifts also increase US options.

So, for the time being, US policy should be twofold: (1) mounting pressure on El Salvador for meaningful reforms, including an end to death squads, and (2) continued pressure on Nicaragua, via the contras, to bring that country to the bargaining table. Finally, it is expected that the Kissinger commission will stress reform and significant economic assistance for El Salvador, as opposed to direct US military intervention. In the long run, that seems the only meaningful US policy for the region.