When U.S. President Joe Biden held a video summit with Prime Minister Fumio Kishida in January, the American president joked that his counterpart should be careful with the incoming U.S. ambassador.

Rahm Emanuel — the former Chicago mayor and long-time Democratic Party insider with a reputation for butting heads — seemed like an odd fit for a diplomatic post in a conservative country where change is often glacial. In the meeting with Kishida, Biden reassured the Japanese leader that Emanuel had his complete trust, according to an official with knowledge of the talks.

So far, Emanuel appears to be causing less friction than during his eight tumultuous years in Chicago's City Hall. Fellow diplomats and Japanese officials say Emanuel’s hands-on approach at least in part explains Tokyo’s surprisingly forceful response to Russia’s invasion of Ukraine.