A U.S. Navy fast-attack submarine arrived in Cuba's Guantanamo Bay on Thursday, hard on the heels of a Russian flotilla's arrival in Havana 24 hours earlier. The USS Helena, one of around two dozen Los Angeles-class nuclear-powered, conventionally armed boats, was making "a routine port visit...while conducting its global maritime security and national defense mission," the U.S. Southern Command (SOUTHCOM) said in a statement on social media. On Wednesday, Cuban armed forces welcomed the...