Donald Trump's trade advisers were finalizing plans on Wednesday for the reciprocal tariffs the U.S. president has vowed to impose on every country that charges duties on U.S. imports, ratcheting up fears of a widening global trade war and threatening to add to already-sticky U.

President Donald Trump could sign an order as soon as Wednesday to require that U.S. tariffs on imports match the tax rates charged by other countries.

Senior aide Peter Navarro is a driver of the idea inside the White House. He pushed for reciprocal tariffs during Trump’s first term.