Bangladesh, Nov. 24 -- A new diplomatic storm has erupted between China and Japan, reigniting long-standing disputes rooted in World War II history, territorial rivalry, and the shifting security landscape of East Asia. At the center of the clash is an obscure but symbolically charged provision of the United Nations Charter-the so-called “enemy state” clause-which China has cited to warn Tokyo against any military involvement in a potential China Taiwan conflict. Japan, under its newly elected Prime Minister Sanae Takaichi, has rejected the reference as obsolete and politically motivated, further straining relations between the two regional powers.

The dispute began shortly after Takaichi-known for her hawkish views on nation...