China expressed "serious concern" over reports that Japan and the US might plan a coordinated response in the event of an armed conflict over Taiwan, AFP reported. "Taiwan is an inseparable part of China," foreign ministry spokesman Liu Jianchao told a regular briefing. "Any arrangement or consideration should respect and abide by the principle of one China." Liu was responding to reports earlier in the day carried by the Kyodo News agency that Japan and the US are considering joint plans to coordinate a response of their armed forces if China invades Taiwan or North Korea strikes Japan. The plan would consider a possible Taiwanese declaration of independence and the use by China of military force against the island, according to the report, which cited unnamed US and Japanese government sources.