Private military contractors who do secret missions for Russia flew into Venezuela in the past few days to beef up security for President Nicolas Maduro. Russia, which has backed Maduro’s socialist government to the tune of billions of dollars, this week promised to stand by him after opposition leader Juan Guaido declared himself president with Washington’s endorsement. Yevgeny Shabayev, leader of a local chapter of a paramilitary group of Cossacks with ties to Russian military contractors, said he had heard the number of Russian contractors in Venezuela may be about 400. Shabayev said the contingent flew to Venezuela at the...