Venezuelan strongman Nicolás Maduro is responding to mass demonstrations by selectively killing civilians. If, as a result, some branch of the military breaks with the regime, the country will descend into civil war. But until then it’s a one-sided slaughter.

It’s also a Cuban proxy war. More than a dozen high-ranking Cuban officers are said to be in Venezuela, along with thousands of Cuban intelligence agents. Their job is to keep Venezuelan army officers under constant surveillance to prevent the feared military uprising...