Now that the elections in El Salvador have essentially vindicated the administration's position, the United States has gained the time to formulate a long-run, comprehensive solution.

A starting point is to define more clearly the American objective.

El Salvador is a piece of the Central American puzzle. Forces of change are sweeping the region. We have to accept social and economic factors as the root of the problem. But the situation is aggravated by a sophisticated campaign encouraged by the Soviet Union through Cuba and Nicaragua.

We are faced with a well-coordinated political warfare strategy on three fronts. The first is in the countries themselves, through the use of terror to aggravate political, social and economic problems. There is a diplomatic front where differences of national interests are exploited. The last front is American public opinion.

The response to the election outcome from Castro and the guerrillas will be a renewal of terror and violence, after a period of regrouping and logistical preparation.

If the authorities that emerge from the election fall into the trap of more blind repression, they will play into the guerrillas' hands. Slowly, popular support will be lost. The progressive destruction of the economic base makes a quick solution imperative. The aid requirements will exceed what we can afford or what Congress will appropriate. If there are continued violations of human rights, the mood will become even worse.

Therefore, assistance must be made contingent on respect for political freedoms, human rights and progress in economic and social reforms. If such conditions are met, we should be prepared to support a policy of denial of military victory to the guerrillas.

This would require a three-pronged effort. Externally, it would involve a quarantine of arms shipments to the guerrillas with an invocation of the Rio Treaty by the Salvadorans.

Internally, it would involve assistance to the armed forces in increasing their operational capability. The completion of training in the United States of 1,500 members of the army in May could have a significant impact.

Politically, there must be a credible offer of external guarantees for guerrillas willing to join the legal political opposition.

This strategy could provide the Reagan administration with a collective international approach instead of having to act alone. Evidence of foreign interference will have to be documented before the Rio Treaty organ of consultation. This will enhance the credibility of the administration's position on Cuban-Nicaraguan intervention before American public opinion. By acting in support of existing inter- American law the administration could dispel fears that it is engaging in covert activities against Nicaragua.

Linkage of inter-American security and political guarantees to the left should be a requirement. This may be hard for the Salvadoran right to accept. However, failing to establish these linkages before we make a military commitment may drag us into support of an uncompromising campaign by the military to crush the guerrillas.

We must make it clear to the new authorities in El Salvador that the time is past when American support, strictly on the basis of an anti-communist stance, can be sold to American public opinion.