Secretary of State George P. Shultz is expected to discuss Nicaragua's request for Soviet-made jet fighters during his meeting this week with Soviet Foreign Minister Andrei Gromyko, State Department officials say.
But Mr. Shultz's objections to the possible deployment of such jets - considered advanced by Central America standards - may be unnecessary. State Department officials say the Soviets have already been warned repeatedly that the US would take strong action if the Soviets supplied Nicaragua with the MIG- 21s.
On Sept. 25, Nicaraguan Defense Minister Humberto Ortega said his country's new military airport at Punta Huete, 20 miles northeast of Managua, would be ready for use by combat aircraft by no later than early next year. Mr. Ortega said Nicaragua is seeking MIG-21 jets from the Soviet Union to station at the new air base.
But a State Department official said it is believed unlikely that the Soviets would send the jets, which are clearly superior to those supplied by the United States to neighboring Honduras.
According to the International Institute for Strategic Studies (IISS), Honduras has more than two dozen combat aircraft, including 10 US-supplied A-37B Dragonfly jets and 12 French-built Super Mysteres. Nicaragua has a much less potent Air Force, which includes several antiquated single-engine jets and propeller-driven T-28D trainers, which could be used as fighter-bombers.
But a State Department background report issued last July charges that Nicaragua now has the foundation on which to build a strong Air Force. According to the State Department, the Nicaraguans have about 120 Soviet-made antiaircraft guns and at least 700 SA-7 surface-to-air missiles. They have received from the Soviet bloc about 10 MI-8 helicopters and six AN-2 light-transport aircraft.
The State Department also charges that the Sandinistas have received four Italian-made trainer/tactical support planes, probably from Libya, as well as helicopters from Libya.
''Preparations for using Soviet fighter aircraft in Nicaragua have been under way for more than three years,'' the State Department report says, with pilots being sent for training to Eastern Europe. It adds that the new military airfield at Punta Huete, when completed, will have the longest runway in Central America - 3,200 meters (slightly less than 10,500 feet) - and will be capable of receiving any aircraft in the Soviet inventory.
Miguel Bolanos, a Nicaraguan defector who had been part of the Nicaraguan security apparatus, said last year in interviews that MIGs assigned to Nicaragua were then stationed in Cuba and that the pilots were being trained in Bulgaria.
The acquisition of MIGs by Nicaragua could rapidly shift the balance in air forces against Honduras, in the State Department's view. According to one official, the Sandinistas could use them for psychological effect, bolstering their own confidence and undermining that of their neighbors.
Some State Department officials say they are convinced that Nicaragua's continuing military buildup is a sign that the Soviet and Cuban-backed Sandinistas are not serious about moving toward an accommodation with their neighbors or with their internal political opponents. Last Saturday, Nicaragua announced that it will accept a draft peace treaty for Central America, which has been proposed by four nations known as the Contadora group. The treaty would call for free and fair elections in the region, ban the construction of foreign military bases, and start a process of withdrawing all foreign troops and military advisers.
''How can the Sandinistas be serious about signing on to the Contadora documents when they continue to build up their military force at Punta Huete and elsewhere,'' says a State Department official.
Should the Soviets send MIG-21s to Nicaragua, it is unclear what action the US would take. Some officials are said to advocate direct American air strikes to destroy the MIGs and put the base out of action. But others apparently favor some use of the US-supported ''contra'' rebels against Nicaraguan facilities. The US is reluctant to telegraph precisely what it would do until the need arises, but one State Department official says simply, ''The Soviets know that if they put the MIGs in, we'll take them out.'' An official says that Mr. Shultz would probably raise the issue with Mr. Gromyko at their meeting on Thursday.
The strongest public warning made to date to the Sandinistas has come from Sen. Daniel P. Moynihan (D) of New York, who said in a statement on the Senate floor Aug. 9 that the development of the airfield at Punta Huete is ''the one event that has occurred in Central America ... that has the potential of transforming a regional crisis into a global crisis.''