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.

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 will impose 25% tariffs on Japan and South Korea next month, prolonging the “Liberation Day” duty pause on those two allies amid trade negotiations. Trump announced the tariffs in letters to Japanese Prime Minister Shigeru Ishiba and South Korean President Lee Jae-myung on Monday.