CNBC reports the White House has escalated the U.S.-Canada trade dispute with
three measures: broadening the list of goods subject to 50% tariffs; specifying
that Section 232 tariffs will be imposed in addition to those duties; and
upgrading some items currently facing 50% tariffs to outright import bans.
Tariff stacking is likely to matter most for steel, aluminium and other metal
products. Officials appear to be invoking bans because the underlying law bars
tariffs above 50% but permits import prohibitions. No estimate has been released
of the trade volume affected. The move represents a clear escalation—the Trump
administration has not previously used trade law to ban imports from a major
trading partner and neighbour.