The administration's forthcoming policy statement on assistance to the Caribbean region will no doubt include recommendations on how we respond to the current struggle in El Salvador and the dramatically altered situation in Nicaragua. It should also speak effectively to the potential for tragedy in Costa Rica.

Since 1948 when the U.S. government lent support to a new Costa Rican government, consolidating its position after a left-wing move to set up a first communist regime in the Western Hemisphere, that small country has been a showplace for democracy in Central America. Over the last 30 years, the Costa Rican standard of living has been the highest in the region, the nation has functioned without need of armed forces, and its level of voter participation has put U.S. elections to shame. Costa Ricans just elected an opposition candidate as its new president, something that would never have happened in many so-called democracies.

But economic problems jeopardize the nation's stability. The price of coffee--long the mainstay of exports--has not kept pace with that of the oil Costa Rica must import. As a result, it has a foreign debt of nearly $3 billion, which is complicated by the fact that its international lines of credit have been virtually closed. In addition, Costa Rica has been unable to meet requirements set by the International Monetary Fund for help in covering financial obligations now outstanding.

The Costa Rican domestic economy has also suffered growing unemployment (nearly 20 percent in a country with a full-employment tradition), more than 40 percent annual inflation, a declining gross national product and the imminent bankruptcy of nearly a third of its businesses. Not surprisingly, the economic pressures have strained the political structure. Strikes have become more frequent as the standard of living has fallen. Last year, sporadic terrorism hit, leaving at least seven dead and threatening traditional protections of human rights. There has even been, according to some reports, open talk of a coup. But, in spite of it all, the democratic tradition of Costa Rica has proven its resilience.

Clearly, the change called for by the Costa Rican voters when they elected opposition candidate Luis Alberto Monge in early February carries with it great expectations and responsibilities. The United States has the opportunity to help this ally succeed as it pursues the democratic principles we have expounded. It is an opportunity to bolster this "model," showing that Third World democracies can survive in bleak economic times. Possibly more important, given our recent past, it also presents an opportunity to show that the United States can be counted on to support a democratic ally before it is embroiled in crisis--that massive dissent, terrorism and even revolt are not required precursors of meaningful U.S. aid.

Our fiscal 1982 aid package will total about $20 million. That pales in significance next to the $800 million in military and economic aid being considered for El Salvador. Yes--in Costa Rica last fall U.N. ambassador Jeane Kirkpatrick did indicate that our aid package could be supplemented with U.S.-sponsored counterinsurgency training. But this is a perfect example of where that approach is not needed. The respect that Costa Ricans feel for human rights is deeply ingrained, at least in part as a result of U.S. urgings. We should not encourage their government to trample on those rights by training forces in skills to do so.

Instead, we should practice a bit of "preventive" foreign policy. We should help the Costa Rican government arrange refinancing of its foreign debt to avoid default, much as we have sought to do for the martial law government of Poland. We should consider reasonable requests for enhanced direct economic assistance to Costa Rica, particularly if we have the means to consider funneling hundreds of millions into El Salvador where the chances of success must be recognized as considerably less. A modest investment today could prevent pouring massive resources into yet another Central American country in a last-ditch effort to prevent the success of a revolution that would jeopardize its democratic principles.

It is good that the administration will shortly be putting our policies in the Caribbean basin in perspective. It is to be hoped that part of that policy will be to maintain stability where it exists. Paying attention to the economic problems confronting Costa Rica today can preserve an important, dependable ally. The president's Caribbean initiatives should not pass up this chance to set things right before they go wrong.