Trump orders another probe asking if metal imports harming nat'l security

April 27 (UPI) -- For the second time in a week, President Donald Trump ordered his administration Thursday to look into the issue of U.S. importing an industrial metal as a matter of national security.

Trump issued a memorandum directing Commerce Secretary Wilbur Ross, Jr., to examine the practice of importing aluminum -- a metal vital to the manufacture of various American defense products.

Ross said the United States essentially has just one smelter of high-purity aluminum due to foreign competition.

"It's very, very dangerous, obviously, from a national defense point of view, to only have one supplier of an absolutely critical material," Ross said at the White House Wednesday.

High-purity aluminum is used to manufacture defense applications like aircraft and armor plating. The evaluation could ultimately lead to a new tax on imported aluminum -- a measure intended to deter reliance on foreign exporters of the metal and spur American-made aluminum.

Eight domestic aluminum producers have closed in the last two years, leaving just two full-time smelters in the United States.

Since taking office, Trump has staunchly supported buying American for a variety of materials. Last week, he issued a similar memo for Ross to look into whether imported steel might also impact national security.

Earlier this year, Trump said he would change government policy to mandate that federal agencies purchase domestic steel for projects like the Keystone XL pipeline.