Sao Paulo, Brazil — United States policy toward Central America and the Caribbean appeared to be undergoing a subtle evolution - in tone, if not also in substance - as President Reagan wound up his five-day Latin American visit with two stops in Central America.
The change in rhetoric was clearly visible.
Although the President minced no words in voicing his belief that Cuba and Nicaragua, and ultimately the Soviet Union itself, were responsible for much of the turmoil stalking the region, he backed away from his administration's earlier, more confrontational approach to the question.
Moreover, in speeches and toasts throughout the trip, Mr. Reagan took time to emphasize the social and economic factors that many Latin American specialists regard as every bit as important, if not more important, than the Cuban and Nicaraguan roles in Central America's current difficulties.
State Department spokesmen deny there has been any major policy shift. Yet they do not reject the notion that an evolution in tone, rhetoric, and emphasis is taking place.
There is some suggestion that Secretary of State George Shultz is responsible for engineering the change. His predecessor, Alexander M. Haig Jr., was more combative and confrontational in his approach - and Central America and the Caribbean were as a result very much in the headlines. The region has clearly been less in the headlines of late, not because of any lessening of the problems there, but rather because Washington was not making as much of them publicly.
There can be no mistaking the Reagan administration's concern over these problems. Mr. Reagan went to great lengths before his trip in answering questions of newsmen from the countries to be visited in placing blame for the turmoil squarely on Cuba and the Soviet Union.
By its support for armed violence and subversion against its neighbors, he said, ''Cuba . . . is indeed a threat to the peace of the Americas.'' But he went further in saying that without the massive $3 to $4 billion in Soviet aid to Cuba, the island ''could not afford to be doing what it is doing.''
Mr. Reagan also emphasized that the US would continue to take measures ''designed to increase the cost to Cuba and its Soviet paymasters'' and ''where necessary, we also (will) provide security assistance.''
This certainly does not suggest a change in direction of US policy toward Central America that, since the Carter years, has supported the efforts of the government of El Salvador to resist Marxist-oriented insurgents who get some of their support from Cuba. But the language now used by the administration is easily less confrontational.
This shift in rhetoric was first noted last August when Assistant Secretary of State for Inter-American Affairs, Thomas O. Enders, spoke in San Francisco and called for an eventual reconcilation among Central American combatants. Then , in October, the US ambassador to El Salvador, Deane R. Hinton, publicly protested against the Salvadoran government's failure to bring to justice rightist assassins of two US land reform specialists and four Roman Catholic church women.
But the most substantive changes in tone and emphasis have come from President Reagan himself, who in stressing social and economic issues, put himself more in the fashion of President John F. Kennedy than some in the Reagan administration realize. Here in Brazil for example, his language seemed to some very much like that of Mr. Kennedy when he announced his Alliance for Progress.
Mr. Reagan used words that were received here with buoyant enthusisam: ''Brazil will build. You will grow. And by your side will be the United States - your partner in the new world, a partner for progress, a partner for peace.''
Perhaps such language was designed for a Brazilian audience. Yet, like so much he said here, the words seem to suggest the evolution in US policy toward not only Central America but all of Latin America.
''The tone certainly is more upbeat, less confrontational than anything we have heard for months,'' admits a State Department spokesman.