Five days after U.S. troops landed in Grenada and faced Cubans in battle for the first time, observers here are beginning to sift out the pluses and minuses to Cuba of the crisis.

Among the benefits perceived by Cubans are a flurry of international support of Cuba and condemnations of the U.S. action by allies of the United States. On the negative side, diplomats here point out, are losses in Cuba's standing among its Caribbean neighbors. Overshadowing all is the grim reality of a military confrontation with the long-time enemy of the Cuban revolution. As Deputy Foreign Minister Ricardo Alarcon put it: "Our relations with the United States are lower than at their lowest point."

Cuba's losses have been great: in less than two weeks, Cuba lost one of its two strongest hemispheric allies.

Both Nicaragua and Grenada had their radical revolutions in the same year, 1979. The following year, Cuba lost its other principal regional friend when prime minister Michael Manley of Jamaica was voted out of power.

Now only Nicaragua is left, and it is increasingly less a source of support than a supplicant of aid.

With the loss of Grenada, Cuba also lost its foothold in the English-speaking Caribbean. Many years have passed since the days when both the revolution here and its leader Fidel Castro were young, and Cuba's goals in the Caribbean have become more modest, according to Caribbean diplomats based here.

"Cuba wants respectability in the region," one diplomat said. "But it took them many years to feel integrated, to build up their airline and trade networks."

Cuba's close links with Grenada, and what is widely reported here as a close personal friendship between Castro and Grenadan prime minister Maurice Bishop, were reassuring departures for Cubans from the revolution's history of regional isolation.

"But the Cubans' knowledge of the English-speaking Caribbean was very new," a diplomat here said. "Now with the Bishop thing and the general disaster in Grenada they must be feeling totally confused."

On the day of the U.S. invasion of Grenada, Cuba was additionally embarrassed by Suriname's decision to downgrade Cuba's diplomatic representation. To make matters worse, the decision was announced on national television by Suriname's ruler, Lt. Col. Desi Bouterse. The Suriname military government had previously declared itself friendly to the governments of Cuba and Grenada.

Alarcon commented that events "suggest a strange connection between what is happening in Grenada and the decision in Suriname."

Cuban intelligence and diplomatic personnel must also acknowledge that they failed to predict accurately the course of events in Grenada. The Cubans must have known that the internal political crisis brewing in Grenada's New Jewel Movement was months old. "Everybody knew that; the place is too tiny not to know," a Caribbean diplomat said.

Yet, at least from their public statements, the Cubans appear to have underestimated the crisis that preceded the collapse of the Bishop government and where it could lead.

Deputy Foreign Minister Alarcon, who appears to have been designated the official spokesman to the U.S. media, has been saying that events have proved that Grenada's leaders were right to arm themselves and stockpile weapons for the population. But there is a touch of regret in his voice when he says that.

The fact is that the stockpiled weapons--Cuban or Grenadan--were not distributed to the population, nor used for the Grenadan leadership's military resistance to the invasion. Cubans are fond of pointing to moral victories at times of trouble. "Turn setbacks into victory" is a favorite slogan, put to great use in 1981. That year the storming of various embassies in Havana by tens of thousands of Cubans seeking to leave the island created Cuba's greatest international embarrassment, but Castro, always fast on his feet, made the decision to allow everyone who wished to leave the island to do so. Then, for good measure, he emptied the country's prisons and delivered Cuba's derelict population to the care of the United States.

Despite U.S. suggestions that Cuba had somehow benefited from Bishop's overthrow, observers here think it was the Reagan administration's decision to invade Grenada that provided the Cubans their first opportunity to extract some profit from a situation they implied was a total loss. Five days into the U.S. invasion, Cuban government officials, people on the street and socialist diplomats all share the same exultant conception: that the use of the 82d Airborne against the small Grenadan Army and what were described here as 100 armed Cubans is a triumph for the forces of socialism.

"Do you know if there is still fighting in Grenada?" a senior socialist diplomat asked gleefully at a diplomatic reception in Havana yesterday evening. On elevators, in buses, in restaurants, at street corners, anywhere a group of Cubans collects, the discussion is the same: "The Yankees have to be taught a lesson. They have to know that they can't invade just like that. If we're fighting them four days in Grenada, where we weren't even prepared, just imagine what we'd do to them if they came here," a telex operator at the Havana Libre Hotel said.

For Cuban officials, the benefits of the prolonged skirmishing in Grenada are more precise. Statements by Castro and Foreign Ministry officials make clear that Castro decided almost immediately after learning of the invasion to instruct the Cubans in Grenada to resist to the death.

The fighting "is intended to have a demonstration effect," Alarcon said. "The Americans now have to think of how many thousands of battalions they would need to subjugate Cuba or Nicaragua if all their technical and logistical strength hasn't enabled them to take Grenada."

Cubans see another victory in the international arena: Cuba can hope to rally Latin America more firmly to its side. The offer by Colombia and Spain to mediate the return of prisoners is seen here as a tacit rejection of the U.S. position. Mexico's strong and prompt condemnation of the U.S. action came at a time when relations between Mexico and Cuba had cooled. Miguel de la Madrid, a year into his presidency, is not the sort of man who would call Castro "brother" as did his predecessor, Jose Lopez Portillo.

"For us, it is now possible to tell Latin Americans that we have not been crying wolf all this time," a Foreign Ministry official said. "Now the whole world can see that Americans will invade, will use force, that we are threatened."

Condemnation of the U.S. action is most satisfying to the Cubans when it comes from U.S. allies. At a diplomatic reception here, reaction to the Grenada invasion among the Western Europeans ranged from "disgraceful" to "ridiculous." The Western Europeans were quick to express their dislike of Castro's Marxist government, and distrust of its motives, but the same diplomats said the Grenada invasion had been a mistake that could lead to a quagmire for the United States.

It is possible that in planning the Grenada invasion the Reagan administration did not foresee the Cuban resistance. Many observers here point to the Cuban attitude toward defeat, the importance they attach to not giving in to pressure, as an explanation for the decision to get involved in the Grenadan fighting.