Why did the United States force Japan to adopt Article IX in their post-World War II constitution?

https://www.quora.com/Why-did-the-United-States-force-Japan-to-adopt-Article-IX-in-their-post-World-War-II-constitution/answer/%E6%A1%91%E7%94%B0-%E5%81%A5%E5%8F%B8-Kuwata-Kenji?prompt_topic_bio=1

It will be declared "not to resist whites again".