President Donald Trump on Monday set a 25% tax on goods imported from Japan and South Korea, as well as new tariff rates on a dozen other countries.

President Donald Trump sent out letters to nations that haven't entered into trade agreements with the U.S., informing them of their new tariff rates.

In letters so far to 14 countries, including smaller exporters to the United States such as Serbia, Thailand and Tunisia, Trump hinted at opportunities for additional negotiations, even while warning that reprisals would draw a like-for-like response.

But after seven rounds of fruitless negotiations and a subsequent letter from U.S. President Donald Trump on Monday indicating that most Japanese goods exported to the U.S. will be subject to higher duties than originally expected, the united front has started to show some cracks.

The US sets reciprocal tariffs of 25% for Japan and South Korea. Both countries vowed to accelerate negotiations within three weeks.

Japanese think tanks warn that the country's economy could take a big hit if the administration of US President Donald Trump implements 25-percent tariffs.

Japanese Prime Minister Shigeru Ishiba called the announcement of slightly higher US tariffs “truly regrettable” while he vowed to continue to protect his nation’s interests in the extended trade negotiations.

The U.S. will impose tariffs of 25% on Japan and South Korea beginning on Aug. 1, President Donald Trump announced on Monday in posts on Truth Social.

By Jeff Mason, Bart H. Meijer and David Brunnstrom WASHINGTON/BRUSSELS (Reuters) -U.S. President Donald Trump opened a new phase on Monday in the trade war he launched this year, telling partners, from powerhouse suppliers such as Japan and South Korea to minor players,

Trump shared screenshots of letters detailing new tariff rates for over a dozen countries, allowing room for further negotiations before the renewed deadline of Aug. 1.