i'm cholaphansa narula in bangkok. >>> pentagon officials say u.s. bombers flew near chinese-built artificial islands in the south china sea earlier this week. last month the u.s. sent a navy destroyer to the area to challenge china's activities there. pentagon officials say that two b-52 bombers left sunday night and returned monday. they say chinese air traffic controllers issued two warnings to the aircraft but the bombers continued their mission. the officials say the aircraft flew over the disputed spratly archipelago but did not go within 12 nautical miles of the manmade islands. one official described the mission as routine. >> we conduct b-52 flights in international air space in that part of the world all the time. >> the u.s. destroyer mission on october 27th did enter the 12-nautical-mile zone around one of the islands. washington argued countries cannot claim the territorial waters surrounding manmade features. >>> japan's defense minister gen nakatani will continue to monitor china's actions after one of the naval vessels was spotted clo