President Donald Trump holds up a proclamation on aluminum during an event in the Roosevelt Room of the White House in Washington, Thursday, March 8, 2018. He also signed one for steel. (AP Photo/Susan Walsh)

President Donald Trump holds up a proclamation on aluminum during an event in the Roosevelt Room of the White House in Washington, Thursday, March 8, 2018. He also signed one for steel. (AP Photo/Susan Walsh)

WASHINGTON (AP) — Unswayed by Republican warnings of a trade war, President Donald Trump ordered steep new tariffs on steel and aluminum imports to the U.S. on Thursday, vowing to fight back against an “assault on our country” by foreign competitors. The president said he would exempt Canada and Mexico as “a special case” while negotiating for changes to therattled allies across the globe and raised questions at home about whether protectionism will impede U.S. economic growth. The president made his announcement the same day that officials from 11 other Pacific Rim countries signed a sweeping trade agreement that came together after he pulled the U.S. out of the Trans-Pacific Partnership last year.

Though he focused on workers and their companies in his announcement, Trump’s legal proclamation made a major point that weakened steel and aluminum industries represent a major threat to America’s military strength and national security.

The former real estate developer said U.S. politicians had for years lamented the decline in the steel and aluminum industries but no one before him was willing to take action.

Despite a week of furious lobbying against his plan by Republican lawmakers