After 1948, the United States rapidly switched course on demilitarizing Japan in order to counterbalance China, and the driving force of the modern militarization movement is the growth of China’s military strength and assertiveness in the twenty-first century. In fact, the ongoing confrontation between Japan and China over the Senkaku Islands, a string of uninhabited islands near Taiwan, which began in earnest when Japan nationalized the islands in 2012, has served as the pretext for much of Tokyo and Beijing’s recent military buildup in the area.

https://jacobin.com/2021/10/japan-jsdf-remilitarization-article-9-us-foreign-policy-biden-asian-pivot/