The U.S. Commerce Department is self-initiating the investigation, which will "examine the domestic production needed to meet all U.S. defense needs, the domestic industry’s capacity to meet those requirements, and the necessary related human needs and resources," CQ Roll Call reported on Thursday. 

Discussing the investigation with reporters, Commerce Secretary Wilbur Ross explained that with domestic steelmakers operating at less than three-quarters of capacity, the worry is that they would be unable to keep up with demand tied to the Trump administration’s planned military buildup, Roll Call said.  

Ross said the investigation was launched Wednesday, and on Thursday, President Donald Trump signed a memorandum asking that investigation be expedited. 

"Maintaining the production of American steel is extremely important to our national security and our defense industrial base. Steel is critical to both our economy and our military. This is not an area where we can afford to become dependent on foreign countries," Trump said during a signing ceremony at the Oval Office. 

The signing was witnessed by several steel executives: Mario Longhi, of U. S. Steel.; Roger Newport, of AK Steel; John Ferriola, of Nucor; John Brett, of ArcelorMittal USA; and Chuck Schmitt, of SSAB Americas. United Steelworkers International president Leo Gerard also was in attendance. 

In a statement, Gerard said he and the union applaud the action. 

"China's continuing overproduction of steel and other products is a particularly intractable problem that has defied solution, despite global efforts to force China to rein in its overcapacity. This investigation, initiated by the administration, should form the basis for taking comprehensive action to ensure that America has the steel it needs,” Gerard said. 

"America's security depends not only on the quality of its weapons, but the critical infrastructure, logistical support and ability to respond in times of crisis. From our weapon systems to the rails and bridges that bring them to our ports, to the pipelines that deliver water and energy to our people, to the steel used in electrical transmission, steel is unquestionably vital to our nation's security. There is no way that we can rely on other countries that cheat for our supplies."

U. S. Steel said it, too, supports the investigation.

“For too long, China and other nations have been conducting economic warfare against the American steel industry by subsidizing their steel industries, distorting global markets, and dumping excess steel into the United States. The effects have been staggering. Tens of thousands of workers in the American steel industry, the industry’s supply chain and the communities in which our industry operates have lost their jobs due to unfair and illegal practices by foreign producers," the company said in a statement. 

But while both called out China for its excess production, Trump declined to say the investigation is aimed at that country.  

“This has nothing to do with China," Trump said at the ceremony, according to The Washington Post. "This has to do with worldwide, what’s happening. The dumping problem is a worldwide problem.”

The investigation is being carried out under Section 232 of the Trade Expansion Act of 1962, which has been used 14 times since it was created, according to USA Today. The law gives the Commerce Department 270 days to complete the investigation; Trump has asked that it be completed in 50, the newspaper said.