The latest information from Nicaragua and from Washington seems to agree that Soviet MIG fighters planes were not aboard the Soviet freighter which was unloading at Corinto over the weekend. But that ship and others have been bringing modern weapons of many types, including combat heliocopters, to Nicaragua from the Soviet Union.
Obviously a substantial Soviet resupply of Nicaragua with modern weaponry is underway.
If MIGs were not in the present lot it is probably because of two reasons. The Nicaraguans are clearly afraid of a US invasion. Their first priority need is for defensive weapons. Also, would the Soviets want to give unnecessary offense to Mr. Reagan now when he and they are maneuvering towards a resumption of a diplomatic dialogue?
The regime in Nicaragua would like to have fighting air power. Its arsenal today has 12 combat aircraft. Nicaragua is outclassed in air fighters by three neighbors associated with the United States. El Salvador has 59, Honduras has 30 , and Guatemala, 16. That gives a total of 105 combat aircraft in pro-US hands, against Nicaragua's 12. Besides, there is usually a US aircraft carrier hovering off shore. A hord of MIGs must be on the Christmas dream list of Daniel Ortega Saavedra, just elected President of Nicaragua.
But there are other things he needs more than MIGs for playing the game he has elected to play against President Ronald Reagan of the US.
Mr. Ortega is trying to sustain himself and his regime independently of the US in a part of the world that is surrounded and dominated by overwhelming US military power. He could be squashed, just as the pro-Castro regime was squashed in Grenada last year, although not as cheaply.
Grenada was defended by a few-score Cubans. President Ortega of Nicaragua has a standing army of 60,000 men, plus 60,000 reservists and 40,000 more in a civilian militia force. He could field a trained military force of more than 100 ,000 men on a few hours' notice. Nicaragua could be squashed - but US casualties in the process would be politically significant.
President Reagan would like to eliminate the Sandinista regime. He has made no secret of his feelings. He has done all that American public opinion and the Congress will allow him to do to bring down that regime. He is being restrained at the moment by repeated votes in the Congress against using US funds to support the counterrevolutionaries (the contras) operating around the fringes of Nicaragua.
To achieve his desire to squash the Sandinistas, Mr. Reagan needs a provocation that would be accepted in Congress, by friendly Latin American governments, and by the NATO allies as justification for US military intervention.
What Mr. Ortega needs is enough rifles and machine guns for his troops to make the prospective price of invasion too high for Mr. Reagan and to avoid at the same time the provocation which in world eyes would justify a US invasion.
Would MIGs suddenly showing up on Nicaragua's airfields be enough justification for US military action? I do not know the answer. Perhaps Mr. Reagan is not himself sure what he would do. But he would have to do something. He is on the public record as saying that the delivery of ''advanced jet fighters'' to Nicaragua would be ''unacceptable.''
Mr. Ortega would be foolish to call Mr. Reagan's hand unless or until he has first built his own defensive position to the point where Mr. Reagan would have to consider very seriously the probable US casualties from an invasion of Nicaragua.
The plausible estimate of the situation is that Mr. Ortega is bringing in as much as he can get from the Russians or others in the way of rifles, machine guns, and other weapons for defending himself from a possible American invasion.
So long as he does only that, Mr. Reagan could invade only in defiance of the Congress and of world opinion. Mr. Reagan does not yet have sufficient justification in those eyes. Mr. Ortega would be foolish to give him such justification.