When President Donald Trump first slapped tariffs on imported aluminum, the goal was clear: Increase domestic aluminum production for national security purposes.
The executive order Trump signed in March 2018 declared that aluminum was being imported in "such quantities and under such circumstances as to threaten to impair the national security of the United States." A Commerce Department report laid out the argument in more detail: If the U.S. found itself in a major war, it would need reliable supplies of aluminum (to make weapons, aircraft, and more) and should not depend on imports to meet that need.
