How it works: Under a 2015 law, in order to be a currency manipulator, a country needs to spend 2% of GDP on currency manipulation over a 12-month period. China is not doing this. If anything, China was keeping the yuan artificially strong until Trump ratcheted up the trade war on Thursday.

Why now: Trump campaigned on labeling China a currency manipulator, but was persuaded not to on the grounds that it would not be helpful. Today, however, voices from both the right (Lou Dobbs) and left (Chuck Schumer) have been urging the president to take this step.

What’s next: The currency manipulator designation does not come with particularly harsh remedies. First comes a year of negotiations, and after that even the Trump administration's proposed beefed-up penalties are small, amounting to no more than about $20 million per year. The move will certainly annoy the Chinese, however, and make any trade deal harder to achieve.