Havana — Jesse Jackson's one-man diplomacy in Central America and the Caribbean has brought a breath of fresh air to this troubled region:
* In El Salvador, the Reverend Jackson's meetings with Salvadorean guerrillas and President Jose Napoleon Duarte have led both to agree, at least tentatively, to talks aimed at scaling down that country's civil war.
* In Cuba, he appears to have started the ball rolling for release of some 21 Cuban political prisoners and for other actions that might lessen tension between Cuba and the United States.
In part the mood of conciliation Jackson seems to stir is political posturing. No commitments have been made and all sides gain from appearing to be willing to talk.
But at the same time there is no masking the clear sense of excitement over his 42-hour stop here in Cuba.
Jackson's words upon arrival Monday were just what the Cubans wanted to hear:
''The people of the US and Cuba need to renew our friendship and our ties. We need to talk with each other, not against each other.''
Cubans recognized that there is a definite domestic political content in the Jackson visit. They know there is an election in the US. They know Jackson is unlikely to win the Democratic presidential nomination, but they see him as an increasingly important force within the ranks of the Democratic Party.
The Cuban government is clearly interested in what the visit of such a major US figure implies for Cuba-US relations. It provides an opportunity for Cuba to talk to the North American public. And it highlights Jackson's view that the US and Cuba should restore normal diplomatic relations.
At time of writing the Cubans had refused to discuss any political prisoner release. They did say, however, that any request for reconsideration of Cuba's decision not to attend the Olympics - a request Jackson is expected to make - would probably be unsuccessful.
Many analysts here are skeptical that any firm progress will be made in El Salvador or in US-Cuban relations as a result of Jackson's whirlwind tour of the region. They say it is important not to expect too much progress, or to expect it quickly. Efforts at improving US-Cuban relations over the past six or seven years have too often gone astray on the shoals of fundamental disagreements over a host of issues relating to Central America, Africa, and other areas of the world.
But many here see the trip as groundbreaking nonetheless.
Still, the upbeat mood in Central America over the trip may be a progressive step in itself.
In El Salvador, President Duarte said he would put Jackson's view to the people, even though they were not new.
If the Jackson visit to Cuba and Central America does indeed break new ground , there is a question whether this results from his diplomatic skill or whether he is acting as a catalyst to bring movement to situations that were already ripe for some sort of diplomatic breakthrough.
It is clearly too early to tell. But at the same time there is a sense here that the Castro and Reagan governments are beginning to make some slight headway on a variety of issues including the return to Cuba of some of the one-time Cuban prisoners who were among the more than 100,000 Cubans who fled this island in the 1980 Mariel boatlift.
The official US reaction to Jackson's trip is expectedly more cautious.
''Fluidity is the key word,'' says a US official in Central America who spoke with reporters in the wake of Jackson's visit to El Salvador and his meeting with President Duarte.
In Cuba, the Jackson trip was the lead story Tuesday in Granma, the main morning newspaper in Havana. The Democratic presidential candidate arrived late Monday to an extremely warm welcoming ceremony by Cuba's top leadership, including President Fidel Castro.
In his words of welcome at Jose Marti airport, Dr. Castro said he had invited Jackson as a sign of friendship toward the people of the US.
All of Cuba's top leaders were on hand to greet the US visitor: Juan Almeida Bosque and Carlos Rafael Rodriguez, both vice-presidents, Jose Ramon Fernandez, minister of education, and Ricardo Alarcon Quesada, vice-minister of foreign affairs, among others.
Also on hand were the top US officials in Cuba: John A. Ferch and James Todd, the chief and sub-chief of the United States Interests Section in Cuba. Jackson spent time Tuesday with members of the small US diplomatic community in Cuba.
Likewise, Cuba's release of a poet held for the last several years in a Cuban jail here was seen as a good omen for the Jackson visit and his plea for the release of additional political prisoners.
Jackson's tour began June 23 in Panama. He will also visit Nicaragua.