An image posted to a Pentagon media site and tweeted by Scottish journalist Ian Keddie, shows the USS Jimmy Carter, a Seawolf-class nuclear-powered submarine, returning to her home port in Washington Tuesday flying the American flag alongside the unmistakable pirate skull and crossed bones, known as the Jolly Roger. The 450-foot-long boat is one of three in its class and is specially modified to conduct some of America’s most covert underwater operations.