Had a random thought.
The Emperors of Japan stopped claiming divine ancestry under pressure of the US occupation force after World War II. Had the United States not pushed the issue, and had the guns to force the issue if it came to that, it would not have happened.
While the fact that it happened in another country might make it technically legal for the US to have done that(by domestic law- I don’t know nearly enough about relevant international law to judge)… that’s a pretty serious violation of at least the spirit of the free exercise clause. Forcing this on an entire country.
Now, Japan appears to be OK with it these days, still, even by our own law we shouldn’t have done it.