President Trump’s latest salvo on trade gives U.S. allies three weeks to achieve what they have failed to do in three months: persuade the U.S. to relax tariffs that would be costly for their export-dependent economies.

Japan, South Korea and a clutch of other countries were told via letters from the White House that they have until Aug. 1 to agree on new trade terms. Otherwise, steep new levies will be imposed on their imports into the U.S.