Soviets Shift Toward High-Profile Role as Peacemaker in Latin America : Diplomacy: The Kremlin is tired of propping up leftist Nicaragua and wants better relations with nations in the region.

After helping persuade the U.S. Congress to stop arming the Contras and “give peace a chance,” President Oscar Arias Sanchez of Costa Rica penned an audacious proposal to Soviet President Mikhail S. Gorbachev early last year.

“I pointed out to him that if he did not do what the Congress had done and stop sending weapons to Central America, he would be responsible for many years of sterile warfare,” the Nobel Peace Prize winner said at the time.

What he got was a disheartening rebuff. It came not from Gorbachev but from the Soviet ambassador. It said Moscow could not stop aiding Nicaragua’s Sandinista army unless Washington withheld military aid from El Salvador, Guatemala and Honduras. It denied that the Soviet Union supports leftist guerrillas fighting those U.S.-backed governments. The letter was “full of cynicism,” Arias said.

But today, after years of discreet involvement as an arms supplier to revolutionary forces in the region, the Soviet Union is shifting to a high-profile role as Central American peace broker. While moving unilaterally to stem the flow of East Bloc weapons, it has offered to help the United States design and supervise a regional treaty reducing weapons stockpiles and national armies.

Foreign Minister Eduard A. Shevardnadze unveiled the initiative here earlier this month as the highest Soviet official ever to visit Central America. He proposed a withdrawal of all foreign military bases and advisers from the region, offered to mediate between the Salvadoran government and guerrillas and said Moscow wants diplomatic relations with all countries in the region.

Behind Moscow’s peace offensive is a mix of motives: a weariness at home with the growing economic burden of propping up Nicaragua, a desire for superpower collaboration on more important matters and a reluctance to abandon its Sandinista allies altogether.

The Bush Administration, having appealed for Soviet cooperation in pacifying Central America, now finds itself cautioning that Moscow might be seeking too active a role in the traditionally American-dominated region.

“We do not believe it is a serious basis for negotiation to assert that the Soviet Union and the United States have equivalent security interests in Central America,” said State Department spokesman Richard Boucher.

But officials in Costa Rica, El Salvador and Honduras, while not disputing Washington on that point, have welcomed Shevardnadze’s initiative as a belated acknowledgment of Kremlin responsibility for what they view, in part, as an East-West conflict.

Addressing the U.N. General Assembly during Shevardnadze’s visit here, Arias hailed Moscow’s embrace of the Central American peace agreement that he forged two years ago. The five-nation accord calls for internal democratic reforms and a halt to outside military aid.

Until the Sandinista takeover here a decade ago, the Soviet Union had minimal interest in Central America. After the Sandinistas first came under attack by the U.S.-backed Contras in 1981, the Soviets became Managua’s main benefactor, providing up to $1 billion in military and economic assistance a year.

The 70,000-member Sandinista People’s Army, the largest in the region, came to be feared by its neighbors as a Soviet-made monster and widely suspected of funneling arms to the Salvadoran guerrillas.

But now the Sandinista revolution’s ideological value has diminished under Gorbachev’s “new thinking,” which is reorienting Soviet foreign policy toward economic priorities.

Still, not until the Contras collapsed as a military threat late last year, and the Sandinistas felt secure, did Soviet policy begin to shift.

The Bush Administration, more than Arias, has extracted Soviet concessions by putting settlement of regional conflicts high on the superpower agenda. Early this year, the Kremlin stopped shipping arms to Nicaragua, but the gesture was undermined by a stepped-up flow of light weapons from Cuba and Eastern Europe.

In Wyoming last month, U.S. Secretary of State James A. Baker III told Shevardnadze that Moscow should persuade its allies to cut off such weapons and move to stop arms traffic to the Salvadoran rebels.

Shevardnadze came here primarily to engineer a suspension of all arms deliveries to Nicaragua, according to two diplomats who were briefed by participants in the talks. But they said he did not press the issue of aid to the Salvadorans, apparently leaving it as a “bargaining chip” for future American concessions.

In separate statements after his two-day visit, Shevardnadze and his hosts said the embargo on arms from the Soviet Union will extend through Nicaragua’s election next Feb. 25. In the meantime, he said, weapons obtained by Nicaragua from any other source will be listed publicly.

The diplomats said this was the Sandinistas’ way of agreeing to renounce all military aid for the next 4 1/2 months--until new negotiations in the post-election period. According to the Soviet press, Shevardnadze got Cuban President Fidel Castro to accept the moratorium during a stop in Havana on his way home.

“The United States is getting what it wants, at least temporarily,” said an Asian diplomat. “If there is a trade-off for Moscow, it must be in Afghanistan. The Soviets are extremely anxious for the United States to cut off military aid to the Afghan rebels and respect the Soviet-backed regime.”

Nicaragua’s economy is so shattered after a decade of war and mismanagement that the Sandinistas had no choice but to accept the arms suspension, the diplomats said.

In return, they reported, President Daniel Ortega won a reluctant pledge from Shevardnadze to maintain Nicaragua’s current level of Soviet economic aid--about $300 million a year--into the next five-year plan, starting in 1991. The Soviets had been trying to avoid a new aid commitment until next year.

“The message from Moscow is clear,” a Honduran official said. “The way to advance socialism is not by military force or monopoly of state power.”

Officials in the region say they believe that message has reached the Farabundo Marti National Liberation Front in El Salvador. Last month, the Marxist guerrilla movement made a peace proposal and opened talks with the country’s new rightist government.

“The Sandinistas must have told (the guerrillas), ‘Look, we have done all we can for you. We have our own problems. Now you are on your own,’ ” said a non-American diplomat with access to the Sandinista leadership.

The diplomat said he believes that Managua has stepped up arms shipments to the rebels in recent months, knowing it will soon have to renounce such aid under U.S. and Soviet pressure.

In private remarks repeated by a Central American diplomat, Shevardnadze said the nine-year-old Salvadoran conflict “serves no interest of Soviet foreign policy.” Soviet sources say Moscow prefers an internal settlement that guarantees a “balance of interests” with no winners and no losers.

Still, U.S. regional allies are skeptical of the Soviet initiative. Salvadoran officials say they are not ready to open diplomatic ties with Moscow, accept its mediation or put much faith in a temporary cut-off of arms to Nicaragua. Insisting that it is too early to judge the Shevardnadze mission, U.S. officials said the flow of arms in Central America will continue to be monitored closely.

Times staff writers Michael Parks in Moscow and Robert Toth in Washington contributed to this report.