In early August, the Cuban Government foiled an attempted coup organized by Cuban exiles in the Dominican Republic. The plotters had enlisted the help of William A. Morgan, an American who had fought with the 26th of July Movement against Batista and who was presently operating a farm in Cuba. Morgan, along with Eloy Gutierrez Menoyo whom the plotters also approached, informed the Cuban Government about the invasion attempt and plans for the coup. The plotters were captured after landing in Cuba and several thousand suspects were imprisoned by the Cuban Government. The attempted overthrow of the Castro government was reported in telegram 360 from Havana, August 11. (Department of State, Central Files, 737.00/ 8-1159)

The U.S. Government obtained information prior to the coup implicating Morgan in some kind of planned activity against Castro. In telegram 150 to Havana, August 2, the Department transmitted the substance of an FBI report that Morgan was the leader of a group planning to assassinate Fidel Castro the following afternoon. (Ibid., 737.00/8-259) In telegram 294 from Havana, August 3, Bonsal reported that he had given the gist of the report to Roa, who expressed appreciation for the information and said it would be conveyed to President Dorticos and to Castro. Bonsal furnished the Department some biographical information on Morgan and said he appeared to be "thoroughly irresponsible and unprincipled." Bonsal said that even an unsuccessful attempt on Castro's life would be a serious threat to the safety of Americans in Cuba. (Ibid., 737.00/8-359)

On August 4 Bonsal called on Roa at the latter's request. Roa said that he had conveyed the information on Morgan to President Dorticos, who was "highly alarmed." Apparently Castro had not yet been given the information, according to Roa. Bonsal stressed that the U.S. Government "had no opinion as to the report's veracity", and that it might be intended simply "to attempt to sow dissension and suspicion." (Memorandum for the files by Bonsal, August 4; Washington National Records Center, RG 84, Havana Embassy Files: FRC 68 A 1814, Political Affairs)

For Bonsal's recollections of the Morgan affair, see Cuba, Castro, and the United States, page 84.