While the surprise 11th-hour trade agreement between Japan and the United States gave the markets reason to cheer after months of anxiety, uncertainty remains, with the fine print of the deal and the implementation of certain pledges in focus.

A massive and unprecedented $550 billion investment plan, in particular, is the subject of doubt and discussion.

Officials in both countries offered more details the day after the world learned the basics and broad outline of what was agreed to in Washington on Tuesday, but many questions were left unanswered.