Vice President Joe Biden, currently on a visit to Japan, has said the U.S. is “deeply concerned” about China’s attempt to exert authority over a new air defense zone its declared above a set of contested islands in the East China Sea. Both the U.S. and Japan have refused to recognize it. Harry Katsianis, managing editor for The National Interest, explains what China is hoping to achieve in the East China Sea. (Photo: A.P./Toru Yamanaka)