One by one, they are singing, the men who used to do dirty deeds for the late Venezuelan dictator Hugo Chavez and his successor, Nicolas Maduro. Nobody knows what’s going to happen, whether the United States will attack, and whether Maduro will fall. But these Venezuelans sniff change in the air. As more countries exit Venezuela’s orbit, more allegations are likely to emerge. Two of the men are in prison here in the U.S.: Hugo “El Pollo” Carvajal, the former spy mastermind, and Cliver Alcala Cordones, a former general, both of whom have written letters to President Donald Trump airing...