In another sign of improving, if not incremental change in relations between the United States and Cuba, the U.S. military formally acknowledged a joint disaster-preparedness exercise last week between American and Cuban soldiers. Troops stationed on the U.S. naval base at Guantánamo Bay crossed over into Cuban territory to set up a mock triage area that would be used by military personnel from both countries, if an actual emergency occurred. Meanwhile, a Cuban military helicopter was allowed to fly over the Navy base to drop water on a simulated wildfire. The exercise itself is not something new, having first been arranged in the 1990s. But last week’s event was the first time anyone on the U.S. side provided details and admitted to the exercise’s existence.