BERLIN (Reuters) - A U.S. soldier stationed in southern Germany was shot dead by police after threatening an ex-girlfriend and then going on the run armed with an assault rifle, authorities said on Friday. The 30-year old, who was serving in the 2nd, "Dagger," brigade of the U.S. 1st Infantry Division, broke into the woman's house late on Thursday, threatened her and tied her up, police in the Bavarian region of Unterfranken said. She was able to free herself and alerted the police, who began a search using a commando unit and a helicopter equipped with thermal imaging equipment. Officers...