American forces successfully tried out Sunday a missile interception system the US hopes to set up on the Korean peninsula, military officials said following a trial just days after North Korea’s second test of an ICBM.In the American test of the so-called THAAD system, a medium-range missile was launched from a US Air Force C-17 aircraft flying over the Pacific and a THAAD unit in Alaska “detected, tracked and intercepted the target,” the US Missile Defense Agency said.