Fu Cong, China's ambassador to the United Nations, at a U.N. Security Council meeting on the 15th (local time), called Japanese Prime Minister Sanae Takaichi's suggestion of "intervening in the event of a Taiwan contingency" an "interference in internal affairs" and demanded that it be withdrawn.
According to Japan's Kyodo News and public broadcaster NHK, at the U.N. meeting held that day on the selection of the next secretary-general, Ambassador Fu said, "Prime Minister Takaichi's remarks have created a serious risk to peace in Asia and the world," and "it is unacceptable that Japan hinted at the possibility of military intervention in the Taiwan issue."
He went on to say that Prime Minister Takaichi's remarks were a "violent interference in China's internal affairs," adding, "Taiwan is Chinese territory and an inseparable part of China." He added, "It also runs counter to the basic norms of international relations based on the purposes and principles of the U.N. Charter."
Earlier, Ambassador Fu also sent two letters to U.N. Secretary-General Antonio Guterres regarding the issue. In the letters, he criticized it as "the first time Japan has revealed its ambition to militarily intervene in the Taiwan issue, the first case of openly challenging China's core interests, and the first instance of making a military threat against China."
In response to Ambassador Fu, Yamazaki Kazuyuki, Japan's ambassador to the U.N., said, "It is regrettable that groundless remarks were made about Japan," adding, "This is unrelated to this meeting, which is discussing the future of the U.N., and it was an inappropriate statement."
Earlier, on the 7th of last month at the National Diet, Prime Minister Takaichi, in response to a question from an opposition lawmaker, said, "If the U.S. military steps in to break a blockade (by China in the Taiwan Strait, etc.), a use of force by China in response is also expected," and, "If China's use of force involves deploying warships, in any view it would be a 'survival-threatening situation' for Japan." A survival-threatening situation is a condition that allows Japan to exercise the "right of collective self-defense."