THE NICARAGUAN government says its enemies on the right, inspired and supported by the United States, are currently pressing a military campaign from sanctuaries in Honduras and Costa Rica. The quotient of truth in these allegations is hard to establish, but let us grant that something is happening. Whose side should Americans be on?

Instinctively, many Americans will go with the guerrillas. By their repressive tactics, their refusal to move toward early elections and their expanding ties with Havana and Moscow, the Sandinistas have dissipated much of the legitimacy they could claim upon winning power three years ago. They are helping sustain the insurgency in El Salvador and supporting guerrilla activities in Honduras and even in Costa Rica, which has no army. It serves no American purpose to see Marxist power ensconced in Managua.

The urge to see the Sandinistas' get a comeuppance, however, does not mean Americans should administer one. The United States is apparently providing covert support for some of the "contras" in Nicaragua. This is wrong. Such is the history of American intervention there that any further hint of it helps to strengthen the Sandinistas' claim to be embattled nationalists and also helps them tighten their internal grip. The suspected presence of former Somoza followers among the attackers allows the Sandinistas to tar all of their opponents, including the democrats, with the Somoza brush. A cynic might argue that these costs are modest when set against the hoped-for benefits of dislodging the Sandinistas, but the scope of the raids seems insufficient for that end.

Another kind of damage is done to American diplomacy. Its prospects in the region depend in critical measure on working in tandem with Latin governments whose proclivities and publics put real limits on the kinds of cooperation they can extend to the United States. The belief in Latin America that Washington is behind the raids into Nicaragua works against the administration's otherwise worthy effort to enlist Latin governments in resolving regional tensions.

This is critical. Like El Salvador's rulers, Nicaragua's rulers hold power by force against a variety of military and political challengers, and should be under pressure to move to an ultimate democratic political solution--and to respect their neighbors. But all pressures are not equal. Latins are not going to rally behind any policy whose cutting edge is an intervention backed by the CIA. Would they rally if the CIA were somehow subtracted from the mix? There's no guarantee, but it would be a better risk.