The president is increasingly threatening other countries with tariffs for issues that have little to do with trade.

The billionaire executive and leader of President-elect Donald J. Trump’s transition team will be charged with promoting U.S. industry and overseeing technology controls on China.

The former president’s past tariffs raised prices for consumers and businesses, economists say. His next plan could tax 10 times as many imports.

American solar manufacturers are pushing for further protections for their new factories against cheaply priced imports from China.

American and European officials are trying to reach agreement on the outlines of a limited trade deal that could help resolve a major rift over...