President Trump said the U.S. will impose steep levies on imports from 14 countries starting next month, heightening pressure on trading partners.

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 plans to impose a 25 percent tariff on goods imported from South Korea and Japan. The levy will go into effect on August 1st, which is when the Trump administration will begin enforcing sweeping tariffs on a wider swath of countries that fail to reach a trade agreement with the US.