Cuba’s government has spent decades recruiting Americans to betray their country. It objects to Secretary of State Marco Rubio inviting Cubans to cooperate with the CIA. Havana apparently believes espionage should remain a privilege of the dictatorship. The Trump administration is right to disagree. Rubio is challenging a comfortable assumption in Washington: that Cuba is too broke to matter. A regime unable to keep the lights on can still penetrate a government, compromise an intelligence officer, and help America’s adversaries. Poverty has never disqualified a country from espionage. It can make espionage one of its more valuable exports. I am...