Documents published in Washington this week reveal Washington's hidden hand behind the coup that toppled Brazil's president 40 years ago.

SAO PAULO - (AP) -- Declassified U.S. government documents published this week by a Washington-based research group point to U.S. preparations in aid of Brazilian coup plotters in 1964 as well as a CIA ''miscalculation'' about possible resistance against a coup, experts said Friday.

Six documents and one audiotape were released by the National Security Archive to the group's website (www.nsarchive.org) to coincide with Wednesday's 40th anniversary of the coup, which led to a 21-year military dictatorship in Brazil. The group is a nongovernmental foreign policy documentation center.

A CIA cable from Brazil, dated March 30, predicted a military coup ''within the next few days.'' The cable added, ``The revolution will not be resolved quickly and will be bloody.''

The coup started the next day. It was over by April 4, when leftist President Joao Goulart flew to Uruguayan exile. No blood was shed.

''The CIA was probably harking back to events in 1961, when the military was deeply divided over the issue of Goulart assuming power,'' said political scientist David Fleischer, who teaches at the University of Brasilia. ``But, just as there was no violence in 1961, there was none in 1964. It was a CIA miscalculation, not for the first time and not for the last.''

Gaudenico Torquato, a historian at the University of Sao Paulo, said, ``They got it wrong. At that time, the U.S. was involved in the feverish competition against communism known as the Cold War. That colored their judgment.''

The documents also show members of the administration of President Lyndon B. Johnson engaging in active preparations to aid Brazil's military coup plotters.

U.S. Ambassador Lincoln Gordon, in a March 27, 1964, cable to the State Department, requested a naval task force and deliveries of fuel and arms to the coup plotters ``to help avert a major disaster here.''

Gordon confirmed preparations to aid the plotters, but added that ``details of Operation Brother Sam have been known for many years.''

''Preparations were made but it proved unnecessary to set the operation in motion,'' he told Associated Press. Secretary of State Dean ``Rusk made it clear that the U.S. would only intervene under certain circumstances. He wanted to make sure there was broad political support in Brazil for the military before advising any intervention.''