An Italian airliner that crashed into the Mediterranean Sea in 1980, killing all 81 people aboard, was shot down by an unidentified military aircraft, according to a five-year investigation, the Corriere della Sera newspaper said Wednesday. "The Itavia DC-9 was shot down by an air-to-air missile," the Milan newspaper reported. "For the first time in nine years the team of six experts named by investigating magistrate Vittorio Bucarelli is about to make official this uncomfortable but explosive truth."