The U.S. government is investigating potential tariff circumvention in imports of hardwood plywood from Vietnam. The widespread use of import duties by the Trump administration may lead to a proliferation of such issues. There has been a clear shift in imports to the U.S. away from Chinese suppliers and toward those in Vietnam. Shipments from China represented 9.3% of U.S. hardwood plywood imports in the 12 months to April 30 compared to 59.6% in 2016. Those from Vietnam increased to 23.8% in the past 12 months from 1.8% in 2016. Shipments from Cambodia also surged. There’s been...