The point: Trump loves holding people to terms they don’t know they’ve agreed to. If he can’t find a loophole to exploit, he may create one.

That might be legitimate in commercial deals. However, it could backfire in unforeseen (and very non-terrific) ways if he tries to pull the same on the government of a foreign country.

I agree that American workers don’t get fair treatment under international trade agreements like NAFTA. Trump wants to renegotiate or withdraw from those trade deals, but the United States’s trading partners naturally object, as do some members of Congress.

But here’s the loophole: It turns out a president can ignore or override many trade agreements without asking anyone’s permission if he finds that they harm U.S. national security.

In those circumstances, a 1962 law empowers him to impose tariffs, quotas, and other trade barriers.

World Trade Organization (WTO) rules let member nations claim a national-security exemption to trade agreements. The provision’s parameters are unclear, because WTO members rarely go to war with each other—but Trump seems ready to test those parameters.

Steel will only be the test case. Rather than work through cumbersome existing processes, President Trump ordered Commerce Secretary Wilbur Ross to study the national-security implications of steel dumping.

Ross should release his findings soon—but we can guess what they will be. As the Washington Post reported last Friday…

Members of the Senate Finance Committee who emerged from a briefing with Secretary Ross Thursday afternoon said it’s no longer a question of whether Trump acts to protect American steel, but how severely.

In other words, the decision is made. Trump’s Terrific Trade Tempest is on the launch pad.