HAVANA -- U.S.-Cuban relations, strained throughout the years of the Reagan administration, have deteriorated further this month with intensely publicized charges of CIA spying here and a retaliatory expulsion by Washington of two Cuban diplomats.

Both sides appear to have taken steps to avoid a complete rupture of already limited relations, however, and Cuban officials say they anticipate no major new move by President Fidel Castro in his annual state-of-the-revolution address on Sunday.

Cuba underlined in diplomatic notes on July 6 and 16 that it had warned the U.S. government repeatedly in private of unacceptable activity by the alleged CIA agents. But according to West European and Latin American diplomats here, the timing of Castro's decision to go public with his evidence suggests that one of his motives was to distract Cubans from economic and political difficulties at home.

Broadcasts by the U.S. government's Radio Marti of material embarrassing to Castro clearly played a role as well.

The downward spiral of relations apparently began with the defection two months ago of Cuban Air Force Gen. Rafael del Pino, a hero of the 1961 battle at the Bay of Pigs, where Cuban forces defeated an invasion by U.S.-backed exiles.

On June 24 Castro denounced del Pino during a four-hour speech that also minutely detailed the corruption of a young man whom Castro once had held up as a model of Cuba's new communist youth.

The target of Castro's wrath, Luis Orlando, was head of Cuban civil aviation. The president accused, and virtually convicted, him of diverting state funds to build a luxurious residence.

Del Pino's defection called into question one of Castro's most persistent claims: the loyalty of his armed forces.

The Orlando corruption case touched another nerve -- the issue of private ownership. Almost 30 years after Castro led Cuba into the communist camp, he has yet to resolve whether Cubans should be allowed to own or improve their own homes.

Two days after Castro's denunciation of del Pino, Radio Marti began beaming to Cuba an exhaustive interview with the defector. He charged widespread discontent in the Cuban armed forces, particularly among those serving in Angola, as del Pino had done.

Radio Marti has broadcast persistently that Cubans returning from Angola have brought home acquired immune deficiency syndrome (AIDS), an issue that the government until recently has avoided. By July 1, Radio Marti had broadcast four installments of the interview with del Pino.

On July 6, Cuban television began the first of six programs entitled "The CIA War Against Cuba," in which it offered dramatic footage of U.S. diplomats, including four accredited to the U.S. interests section here, making furtive drops of bulky packages, allegedly containing cash and communications equipment.

Cuba sent a message informing the U.S mission earlier that day of its plan to air the program, and it later published the note.

Film from cameras hidden at what were described as isolated drop sites and subsequent testimony of Cuban double agents added credence to reports here that the U.S. clandestine operations had been thoroughly compromised during the 10 years since the two countries established interest sections in each other's capitals.

Granma, the official daily newspaper of the Communist Party Central Committee, published names and photos of 83 persons it alleged were agents either stationed or in transit here during the past decade.

While the televised film appeared to catch U.S. envoys in suspicious activities, no evidence has yet been offered to substantiate an accompanying allegation that the CIA recently has resumed efforts to assassinate Castro. Congress has previously reported such efforts by the CIA in the early years of Castro's rule.

On July 14, the U.S. mission protested the broadcasts, charging that they had endangered the lives of those "catalogued as agents of the intelligence services of the United States" and had made them a "target of terrorists everywhere."

The note did not address the specific activities of the filmed envoys. It charged that all functionaries, "without exception," in the Cuban interest section in Washington were members of the Cuban intelligence service. It ordered two of them to leave by today or be declared persona non grata.

The U.S. mission's public information officer, Donald Sheehan, was among those accused by Cuba of being a CIA agent. His post would be an unusual cover for an agent, and he denies being one. Sheehan has served here two years and is expected to leave shortly, two weeks ahead of schedule. Another accused U.S. envoy left on Wednesday, a third is about to leave as scheduled and the fourth is expected to serve here another year, according to mission sources.

U.S. officials acknowlege that their effectiveness here has been curtailed. Two ambassadors of countries friendly with the United States expressed dismay at what they described as obvious misdirection of U.S. activity here.