President Donald Trump cranked up the pressure on two of America’s key trading partners, Japan and South Korea, firing off letters Monday to the heads of their countries that informed them of their new tariff rate.

President Donald Trump announced tariffs of 25% on goods from Japan and South Korea beginning on Aug. 1, as he moved to impose unilateral rates on countries that have not yet secured trade deals with his administration.

President Donald 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.