The United States has flown two warplanes over the disputed East China Sea, defying a recent edict from China. The Chinese government said over the weekend it must be notified of any flights over part of the small island chain that is also claimed by Japan. The Pentagon says it flew two B-52 bombers as part of a previously scheduled exercise. The United States, Japan and several other governments have rejected China’s claim to an “air defense zone” over the area.