The low-cost shipments were previously excluded from tariffs; President Trump said the loophole has allowed countries to avoid taxes and smuggle drugs into the U.S.

President Donald Trump has announced a flurry of trade activity ahead of Friday's official start of his new tariffs regime — executive actions including 50% tariffs on Brazil, a 15% tax on American imports from South Korea and an end to exemptions for imported goods worth less than $800.