Trump has invoked "national security" both rhetorically and legally to justify the coming tariffs on steel and aluminum imports, but the Washington Post reports that the secretary of defense himself has argued against imposing tariffs as recently as yesterday morning.
Mattis and Rex Tillerson both reached out the White House yesterday and were met by the deaf ears of Trump's new best buddies Wilbur Ross, Robert Lighthizer and Peter Navarro.
Defense Secretary Jim Mattis and Secretary of State Rex Tillerson privately warned senior trade officials on Tuesday that President Trump’s proposed tariffs on steel and aluminum could endanger the U.S. national security relationship with allies, according to five people familiar with the meeting.
The last-ditch efforts to get Trump to scale back, if not reverse, the tariffs came after a power struggle within the White House where Cohn, Mattis and others routinely tried to dissuade Trump from launching what many fear will be a trade war that could rattle the world’s largest economies. [...]
On Tuesday, Mattis and Tillerson met with Ross and Lighthizer to try yet again to change Trump’s mind.
“In a broad discussion, the secretary raised concerns about tariffs that had been mentioned to him by some allies, or are likely to be mentioned,” said Steven Goldstein, the State Department’s undersecretary for public diplomacy and public affairs.
Tillerson and the State Department have come out against Trump's plan because there is no plan. Trump made the announcement last week without any input from the State Department, the Department of Defense, or even some of his own advisers in the White House.
Trump and his new favorites in the White House have repeatedly said they're going show the world that American is going to get stupid "get tough" on trade, but there's no diplomatic plan in place for actually following through on that. They seem to believe rhetoric and poorly thought out tariffs alone are enough to force some kind of change that is favorable to imaginary Americans that will benefit from it.
Now, this is purely speculation on my part, but I believe Trump's tariffs could be vulnerable to legal challenges.
Trump is invoking Section 232 of a 1962 law that allows him to impose tariffs for "national security" reasons but, as far as we know, the National Security Council had no input on his decision and neither did the Department of Defense. Defense Secretary Jim Mattis says the tariffs may actually harm national security.
If private companies challenge the tariffs in federal court or if our foreign trading partners file complaints at the World Trade Organization, the complete lack of credible justification for the tariffs will almost certainly come up.
Trump has no credible justification for anything he does. It's all about his feelings and whims and a desire to only pick fights he thinks he can win.