A small unit of Australian combat troops for the first time took part in a landing exercise held as part of annual South Korea-U.S. drills, a military official said Saturday.The 18-member army unit participated in the maneuvers held recently near the southeastern city of Pohang, the official with the Korea-U.S. Combined Forces Command said. The month-long landing exercises, which began April 5, involve about 3,000 South Korean and U.S. marines