Trump uses tariffs as a key tool to force changes to U.S. trade relationships, but his on-again-off-again approach has roiled markets and stoked uncertainty.

President Donald Trump issued separate letters to the president of South Korea and Japan's prime minister on Monday, saying the U.S. will start charging a 25% tariff on Aug. 1.  "We must move away from these longterm,

The U.S. will put in place a 25% tariffs on imports from Japan and South Korea starting on Aug. 1, according to letters posted by President Donald Trump on his social media platform on Monday. Trump wrote to Japanese Prime Minister Shigeru Ishiba and South Korean President Lee Jae-myung to inform them of the news, citing unfair trade balances.