WASHINGTON (AP)   Concerned that U.S. troops are already saddled with too much heavy gear, military officials will not require them to wear improved body armor until manufacturers cut the weight of the new protective plates. The Army plans to buy 120,000 sets of the advanced bullet-blocking plates this year. This initial purchase of the plates, known as “XSAPI,” will be stocked in Kuwait and be available if commanders need them, service officials said at a congressional hearing Wednesday.