President Trump has announced that section 232 duties on steel and aluminum will be doubled for exports from Turkey. That forms part of a widening set of sanctions against Turkey and is an innovative use of the national-security basis for section 232 duties. Presumably the use-case could be widened to other American sanctions targets including Russia and represents another source of corporate supply chain. Turkey is a relatively small part of U.S. steel and aluminum imports with $938 million of exports having represented 2% of the total in the 12 months to June 30. Yet, there could be...