NICARAGUA's expulsion of eight United States diplomats was an unnecessarily harsh act. It is likely to backfire. That and other repressive Sandinista actions this week bolster the Reagan administration's flagging case for more US military aid to the contras just as surely as have some of Nicaraguan President Daniel Ortega Saavedra's poorly timed visits to Moscow. The US Senate swiftly voted to warn Managua that more contra aid is likely unless the Sandinistas mend their ways.
The Reagan administration reacted by ousting eight Nicaraguan diplomats, including Ambassador Carlos Tunnermann. Fortunately, neither side has seen fit to break diplomatic relations; the ties benefit each.
Managua's expulsions were part of a broader crackdown. After a particularly spirited demonstration in Nandaime last weekend and government efforts to suppress it by tear gas, beatings, and arrests, the Sandinistas shut both La Prensa and the Roman Catholic radio station.
The US diplomats are charged with directly contributing to the turmoil. US officials deny the charges; they do concede that US Ambassador Richard Melton, a former aide to the State Department's Elliott Abrams, had had more contacts with the opposition and fewer contacts with the Sandinistas than his predecessors.
The Sandinistas, ever suspicious of what their enemies may be plotting, may have assumed that the US was moving to a new phase of stirring up the opposition, a tactic tried while Salvador Allende was at Chile's helm. Many Sandinista opponents now call for a ``government of national salvation.''
The need is to keep tempers cool and thinking clear. The prospects for the kind of full and instant democratization the contras press for are slim. The Sandinistas appear ready to agree to limited pluralism, keeping a predominantly one-party state along the lines of India or Mexico. Some press freedom and release of political prisoners would likely be accepted.
But short of an overthrow, the Sandinistas are unlikely ever to sign on to the full range of classic ``democratic'' markings, including a new constitution, a call for early elections, and permission for drafted military recruits to return home.
Repeated Sandinista attempts to resume cease-fire talks, in recess for the last month, have met with no success.
Recent reports that the Reagan administration is leaning toward a policy of greater emphasis on diplomatic than on military pressure are encouraging. Secretary of State George Shultz, who recently visited Central America, is said now to favor a ``final'' negotiations push in early September - one aimed at getting a timetable for Sandinista compliance with specific demands of the Arias peace treaty.
Hard-liners on both sides will have to give. For their part, the US and the contras should carefully weigh the extent and speed of democratic reform they can realistically expect the Sandinistas to accept.
Just as glasnost has worked its chemistry in the Soviet Union, so a democratic start in Nicaragua could in time develop its own dynamic. Options otherwise are continued war or a US overthrow. The diplomatic expulsions would serve some purpose if, rather than generating a new supply of contra aid, they prompted a needed reassessment of what is desirable and achievable.