President Trump on Monday placed a 25% tax on goods imported from Japan and South Korea, citing persistent trade imbalances with the two crucial U.S. allies in Asia.

The president has already threatened an additional 10% tariff on goods from countries aligning themselves with a bloc of nations that includes China and Russia.

The tariffs on two of America’s closest allies would go into effect Aug. 1, unless the countries reach some kind of trade agreement with the United States.