When President Donald Trump revealed that his administration had struck a "massive" trade and investment deal with Japan, he described it as "completed"—but it must still pass the Japanese parliament, called the Diet, which is riven with political turmoil.

The deal imposes 15% tariffs on Japanese cars and other goods, one of the more favorable rates. While the start date and other basic elements are still unknown, Treasury Secretary Scott Bessent warned this week that the US would monitor implementation and bump the rate up to 25% if Trump isn’t satisfied.