US Presses Moscow to End Military Aid to Nicaragua. Soviets appear unimpressed by recent Washington `ultimatums'. US-SOVIET RELATIONS

FOR several weeks now, the Bush administration has been prodding Moscow to cut military aid to Nicaragua. If the Soviets were to oblige, says a State Department official, it would send important signals to the Sandinistas: that they must follow through on internal democratization; that Soviet largesse has reached its limit; and that the Sandinistas must face a decline in their war-making capabilities.

What's in it for Moscow? Washington has been studiously vague on this. Accommodation would encourage an overall improvement in relations, United States officials say. A nonresponse will have ``repercussions,'' they add ominously. They won't say how long the Soviets have to pass this test of their so-called ``new thinking''.

But, says the official at State, Washington is approaching this the way it did Soviet human rights; that is, to keep raising the issue until the Soviets understand how important it is to the US. Then, this reasoning goes, Moscow will find a way to oblige. When Secretary of State James Baker III visits his Soviet counterpart in Moscow next month, Nicaragua will be an important agenda item, the official says.

So far, Soviet officials here, as well as visiting Soviet experts on Latin America, are not impressed by Washington's demands. They resent being given ultimatums.

``This can only lead us back to the times of early Reagan,'' says Sergo Mikoyan, editor of the Soviet journal Latin America.

``The US has no right to demand,'' says Mr. Mikoyan, who notes he is speaking for himself and not his government. ``If the Americans could say that they behave in accord with the agreements on Afghanistan that they signed only last year, well, then. This is my first consideration, and the second is that they have no right to demand we stop military aid to Nicaragua [while] there is a massive military buildup in El Salvador and Honduras.''

It appears the Soviets are still considering how to react to Washington's new Nicaragua policy. Says a Soviet diplomat: ``Not everything is clear in US policy.''

The Soviets appear to be approaching policymaking on this issue with their usual caution. And, suggests another visiting Soviet specialist on Latin America, perhaps Gorbachev needs to protect himself politically from hard-liners by not appearing to give in to US wishes too quickly.

In raising the heat on the Soviets, Secretary Baker may also be protecting his conservative flank. In last month's bipartisan accord on policy toward Nicaragua, he made concessions to the Democratically-controlled Congress.

Over the last 30 years, and especially the last 10, the Soviets have made themselves a player in Latin America, and with relatively little cost (Cuba's $5 billion annual subsidy aside) or effort. Castro took over in Cuba without Soviet help, as did the Sandinistas in Nicaragua. In fact, until 1978 the Soviet government referred to the Sandinista rebels as a ``Maoist sectarian splinter group.'' The two revolutionary, anti-American governments were happy to accept Soviet assistance. Thus, the Soviets gained a foothold to gather intelligence and increase US military expenses.

From Nicaragua, for a yearly $1 billion donation of oil, grain, and old-style military equipment, the Soviets have helped embroil the US in its most emotionally-wrenching foreign policy issue (and biggest scandal) of this decade. Fears of a Cuban- and Nicaraguan-backed Marxist victory in El Salvador's civil war have produced a further drain on US resources.

The Soviets have also made diplomatic gains throughout Latin America in recent years. Ilya Prizel, a specialist on Soviet-Latin relations at the Johns Hopkins School for Advanced International Studies, says that by building ties to Costa Rica, Honduras, and Guatemala, the Soviets helped to create the climate in Central America that allowed regional peace efforts to take root. From that flowed the decline of the US-backed contra war against the Sandinistas. In South America, the Soviets have forged relations with the large industrial states of Brazil and Argentina, with whom the Soviets are eager to boost trade. Both also may provide technology.

Soviet officials, including Gorbachev, insist they have no desire to threaten legitimate American interests in the Western Hemisphere. In El Salvador, the country that frightens the US most as the next possible candidate to ``fall,'' the Soviets say they do not favor a violent takeover by the rebels. North Americans may dismiss such assurances as rhetoric, but at least one new factor in domestic Soviet politics may work in the US favor: the role of public opinion in foreign policy.

Over the last year, Mikoyan says, public opinion has played a ``rapidly increasing role'' in the Soviet Union. ``And I must confess,'' he says, ``there are people who think, `Enough activities abroad,' that we must be active inside, that we have much more important things to do'' at home.

Soviet citizens are not shy about expressing frustration over their government's costly subsidy of Cuba. One song of praise for Cuba that begins, ``Cuba my love, island of purple dawn. ... '' is sometimes revised to go: ``Cuba, give back our bread; Cuba, take your sugar; Cuba, Khrushchev is long gone; Cuba, get lost.''

The point about sugar may be ironic, but the overall sentiment holds: no more third-world basket cases, please.