China-Japan diplomatic tension

China-Japan relations have worsened after Japanese Prime Minister Sanae Takaichi said that any conflict in the Taiwan Strait would be a "survival-threatening situation" for Japan - a legal phrase that implies Japan could intervene militarily if fighting breaks out over Taiwan. Beijing has denounced the remark as a severe violation of the one-China principle and gross interference in China's internal affairs. How has the Japanese Prime Minister triggered such a storm? What does it reveal about Japan's shifting security posture? And where might this confrontation lead?