WASHINGTON/BRUSSELS (Reuters) -- President Donald Trump said on Monday the U.S. would impose a 25% tariff on imports from Japan and South Korea beginning Aug. 1 as he unveiled the first two of an expected 12 letters to trading partners outlining the new levies they face.

White House Press Secretary Karoline Leavitt shows a signed letter on tariffs from US President Donald Trump to South Korean President Lee Jae Myung during a press briefing at the White House in Washington, D.C., Monday. (Reuters via Yonhap)
White House Press Secretary Karoline Leavitt shows a signed letter on tariffs from US President Donald Trump to South Korean President Lee Jae Myung during a press briefing at the White House in Washington, D.C., Monday. (Reuters via Yonhap)

"If for any reason you decide to raise your Tariffs, then, whatever the number you choose to raise them by, will be added onto the 25 percent that we charge," Trump said in letters to the leaders of the two Asian countries, which he posted on his Truth Social platform.

Later, Trump also announced the U.S. will impose 25 percent tariffs on Malaysia and Kazakhstan, 30% on South Africa and 40% on Laos and Myanmar.

The rate for South Korea is the same as Trump initially announced on April 2, while the rate for Japan is 1 point higher than first announced. A week later, he capped all of the so-called reciprocal tariffs at 10% until July 9 to allow for negotiations. Only two agreements have so far been reached, with Britain and Vietnam.

There was no immediate response from the Japanese or South Korean embassies on the announcement.

About 12 countries will receive letters from Trump, White House spokeswoman Karoline Leavitt said at a briefing without identifying them. She said Trump would sign an executive order on Monday formally delaying the July 9 deadline to August 1.

"There will be additional letters in the coming days," Leavitt said, adding that "we are close" on some deals.

The European Union will not be receiving a letter setting out higher tariffs, EU sources familiar with the matter told Reuters on Monday.

U.S. stocks fell in response, the latest market ruction since Trump unleashed a global trade war on his return to office in January. His moves have repeatedly whipsawed financial markets and sent policymakers scrambling to protect their economies.

U.S. stocks were driven to near bear-market territory by his cascade of tariff announcements through the early spring but quickly rebounded to record highs in the weeks after he put the stiffest levies on hold on April 9.