In slapping duties on steel and aluminum nearly seven years ago, Trump reached into the federal government’s tariff toolkit and pulled out Section 232 of the Trade Expansion Act of 1962. Section 232 gives the president the power to impose tariffs on other countries national security grounds.

The president imposed a 25 percent tariff on global metals, repeating a move from his first term. Economists and foreign governments know what will come next.

President Donald Trump moved to substantially raise tariffs on steel and aluminum imports on Monday, cancelling exemptions and duty-free quotas for major suppliers Canada, Mexico, Brazil and other countries in a move that could boost the risk of a multi-front trade war.

The 25 percent tariffs on imported steel and aluminum are the latest salvo in his ongoing effort to overhaul the U.S. trading relationship with the rest of the world.