That Fox News could cause such a stir is a testament to the refusal of mainstream news organizations to verify sources. In all of the iterations of the "Cuban troops in Syria" fantasy, there are no news sources cited. The original Fox News report cites one anonymous U.S. official who may, or may not even exist. The only source on record with their incredulous claims is someone from the Institute for Cuban and Cuban-American Studies (ICCAS) at the University of Miami.
ICCAS is notorious for its reactionary, anti-Communist politics revered among the fanatically right-wing Cuban and Cuban-American population in Miami. Their academic research includes a conspiracy theory that appears to implicate Fidel Castro in the assassination of John F. Kennedy.
Another ICCAS report claims "the often-repeated view in many countries that the United States is an evil power, guilty for much of the problems and sufferings of the developing world, is owed in great part to the propaganda efforts of Fidel Castro" - not, rather, to decades of direct U.S. military intervention; profligate support to fascist military dictatorships; and predatory, neo-colonial lending policies that demand neoliberal structural adjustment programs which funnel public assets and resources to creditor interests, at the expense of the employment, health and well-being of the vast majority of local populations.
Cuban Prensa Latina reporter in Syria Miguel Ferna'ndez noted that ICCAS has reported six or seven times since 2006 that Fidel Castro has died. He suggested reports such as those originating with ICCAS about Cuban troops in Syria were part of the campaigns of reactionary groups opposed to normalization to tarnish the new relations between Cuba and the United States.
The Cuban Embassy in Damascus reportedly "laughed" at the report of Cuban troops in Syria, and told Sputnik News: "It's pure lunacy. It is as if they were claiming that Russia had sent its troops to Madagascar to protect lemurs."
 Gleijeses, Piero. Visions of Freedom: Havana, Washington, Pretoria, and the Struggle for Southern Africa, 1976-1991. The University of North Carolina Press, 2013. Kindle edition.
 as quoted in Gleijeses, 2013