Here is a quote from THE MITROKHIN ARCHIVE by KGB archivist Vasily Mitrokhin who defected to Britain in 1992:
“By 1976 Cuban intelligence was pessimistic about the prospects for challenging American influence in South America. Manuel Piñeiro, head of the Departamento de America, which was responsible for the export of revolution...said only Guyana was following an anti-imperialist course. 'Forbes Burnham, the Prime Minister of Guyana, shares some of the ideas of Marxism-Leninism, but for tactical reasons is forced to conceal this.'
The Soviets agreed with Piñeiro's assessment. In Burnham's Guyana the Soviet Union decided to build their largest embassy in the English-speaking Caribbean. Piñeiro, also called Red Beard, was head of Castro's security for a long time. He died in 1998.