Why it matters: These tariffs have the potential to roil markets and affect relationships with allies. Trump is also touching the third rail of international trade law — he’s using an arcane trade law known as Section 232 to justify his actions. He’s saying “F You” to the World Trade Organization and arguing the global overproduction of steel and aluminum constitutes a national security threat to the U.S. He's also breaking with Capitol Hill and top officials — including Gary Cohn, James Mattis, Steven Mnuchin and Rex Tillerson — who have been arguing strenuously against these tariffs.
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