A Washington-based research group has released documents showing former President Lyndon B. Johnson was willing to back the forces that ousted Brazilian President Joao Goulart in a 1964 military coup.

The independent National Security Archive of George Washington University released the recently declassified documents Wednesday, on the 40th anniversary of the coup.

The research group says in one document, President Johnson instructs his aides to quote - "take every step we can, be prepared to do everything we need to do."

The group says the documents include cables sent by the then U.S. Ambassador to Brazil (Lincoln Gordon), urging Washington to become directly involved in supporting coup plotters led by Army Chief of Staff General Humberto Castello Branco.

Cables from the ambassador called for quote - "a clandestine delivery of arms" - for use by the coup plotters.

The Archive also released a declassified audio tape of President Johnson speaking with national security aides about the situation. On the tape, President Johnson authorizes then Under Secretary of State George Ball to actively support the coup if U-S backing is needed.

The research group, however, says U-S military support for the coup proved unnecessary because the plotters succeeded in overthrowing President Goulart much faster and with much less armed resistance than American policy makers anticipated.

The Archive says the United States viewed Mr. Goulart as a leftist closely associated with Brazil's Communist Party. He fled to exile in Uruguay in April 1964. The Brazilian military held power until 1985.

Some information for this report provided by AP.