China's air force said today that it had flown more than 40 bombers and other fighter planes through a strait between Japanese islands on their way to drills in the Western Pacific. <br/><br/>Regular long range drills in the Western Pacific and patrols over the East China Sea air defence identification zone were for the Air Force to protect China's sovereignty and national security. China drew condemnation from Japan and the United States in 2013 when it imposed an Air Defence Identification Zone in the East China Sea, in which aircraft are supposed to identify themselves to Chinese authorities. <br/><br/>China's ties with Japan have been strained by a longstanding territorial dispute over a string of islets in the East China Sea, known in China as the Diaoyu and in Japan as the Senkaku.