On Thursday President Trump is expected to sign an executive order that could have the effect of curtailing imports of foreign steel.

U.S. President Donald Trump on Thursday will sign a directive asking for a speedy probe into whether imports of foreign-made steel are hurting U.S. national security, two administration officials said on Wednesday.

Trump is to sign the memorandum related to section 232 of the Trade Expansion Act of 1962 at a White House event that is expected to include leaders of some U.S. steel companies. The law allows the president to impose restrictions on imports for reasons of national security.

There are national security implications, one of the officials said, from imports of steel alloys that are used in products such as the armor plating of ships and require a lot of expertise to create and produce.

This is not protectionism, per se, though it could definitely pass for protectionism in dim light.

The purpose of the investigation is to determine the effect of imports on the national security. Investigations may be initiated based on an application from an interested party, a request from the head of any department or agency, or may be self-initiated by the Secretary of Commerce.

The Secretary’s report to the President, prepared within 270 days of initiation, focuses on whether the importation of the article in question is in such quantities or under such circumstances as to threaten to impair the national security. The President can concur or not with the Secretary’s recommendations, and take action to “adjust the imports of an article and its derivatives” or other non-trade related actions as deemed necessary.

At one time, production of steel was used to gauge the military might of a nation. As alloys and polymers have become more common, the use of steel has declined. Oddly enough, it is the decline in steel usage that has brought on the investigation:

The United States imported about 30 million metric tons of steel in 2016, down from 35 million in 2015, for use in a variety of sectors including buildings, bridges, water and sewage plants and oil and natural gas production. Major foreign suppliers include Canada, Brazil, South Korea, Mexico, Japan and Germany.

China is relatively far down on the list because of a number of U.S. countervailing and anti-dumping duty orders already in place on its exports.

Ironically, the last 232 investigation was ordered by George Bush in 2001. The product was steel.