A White House trade official has talked of “exemptions” as opposed to “exclusions” as he was questioned about how steel and aluminum tariffs might affect Canada. Peter Navarro referred in one instance to what Canadian Press calls “key industries.” This seems to refer to auto manufacturing. A tariff on steel and aluminum would play havoc on cross-border supply chains that use steel and aluminum. “There’s a difference between exemptions and country exclusions,” Navarro said on CNN. “There’ll be an exemption procedure for particular cases where we need to have exemptions so business can move forward. But at this point in time there would be no country exclusions.” What this means remains unknown until later this week when clarifications are expected.