NEW : His critics said at the time that he gave in to U.S. pressure , and his governing coalition broke up . Japanese defense minister says officials are lodging protests with U.S. authorities . The two 23-year-olds are accused of raping a Japanese woman on Okinawa . Japan has been under pressure to take stronger action against the men who have taken part in an alleged "comfort women" system that forced women and girls into sexual slavery for decades. The U.S. government is `` extremely concerned '' by the allegations , ambassador says .
NEW : Japanese defense minister says officials are lodging protests with U.S. authorities . The two 23-year-olds are accused of raping a Japanese woman on Okinawa . Japan has been under pressure to take stronger action against the men who have taken part in an alleged "comfort women" system that forced women and girls into sexual slavery for decades. The U.S. government is `` extremely concerned '' by the allegations , ambassador says .