China is watching reports of a draft joint operation plan between the U.S. and Japan closely, Chinese Foreign Ministry spokesperson Zhao Lijian told reporters on Friday.

Japanese and U.S. armed forces have drawn up a draft plan for a joint operation in the event of a "Taiwan emergency," according to a report by Japan's Kyodo News Agency on Thursday that cited unnamed Japanese government sources.

Stating that the country is closely following the situation, Zhao reiterated the Taiwan region is an integral part of China and that China does not allow any countries to interfere in its internal affairs in any forms and with any excuses.

He warned relevant parties not to underestimate the determination, will and capability of the Chinese people to defend the country's national sovereignty and territorial integrity.