US President Donald Trump unveiled new tariffs against more than a dozen countries on Monday as he increases pressure on America's trade partners to negotiate on deals.
In the letters posted on his Truth Social media platform, Mr Trump said he was imposing the harsher tariffs than had been postponed from April.
The White House said Mr Trump is delaying the deadline to impose the harsher deadlines until August 1.
Tunisia, Japan, South Korea, Malaysia and Kazakhstan were all hit with tariffs of 25 per cent. Mr Trump announced tariffs of 30 per cent on Bosnia and Herzegovina and South Africa, 32 per cent on Indonesia, 35 per cent on Bangladesh and Serbia, 36 per cent on Cambodia and Thailand, and 40 per cent on Myanmar.
In the letters, which were worded almost identically for each country, he warned the receiving countries' leaders to announce retaliatory measures.
“If for any reason you decide to raise your tariffs, then, whatever the number you choose to raise them by will be added on to the 25 per cent that we charge,” he wrote in a letter to Tunisian President Kais Saied.
Other countries were threatened with similar retaliatory tariffs. Mr Trump said he would be willing to adopt lower rates if countries adjust their trade policies.
"We will, perhaps, consider an adjustment to this letter," he wrote.
South Korea said in a statement that it would engage in trade negotiations with the US to advance both countries' key industries, Reuters reported.
US markets closed in the red amid the tariff developments, with the Dow Jones Industrial Average closing 422 points – or 0.94 per cent lower. The S&P 500 and Nasdaq Composite fell 0.79 and 0.92 per cent.
Mr Trump had said he would be issuing letters to trading partners starting this week with countries that would dictate their tariff rate.
The tariff rate on Tunisia was three percentage points lower than Mr Trump had announced on April 2.
The 25 per cent tariff on South Korean imports mirrored what he had previously announced on April 2, while the tariff rate on Japan was one per cent higher than Tokyo's initial “reciprocal” tariff.
Those reciprocal tariffs, along with dozens of others, were then delayed for 90 days after turmoil in financial markets that prompted Mr Trump to reverse course.
His shifting trade policy began a new era of uncertainty in the global economic outlook, with central bankers and economists trying to understand how the effects of tariffs will relate to the cost of goods, hiring and firing practices, investment and more.
Earlier on Monday, Treasury Secretary Scott Bessent said Mr Trump's administration expected to make “several” trade-related announcements in the next two days. As of Monday, the US had only agreed to trade deals with the UK and Vietnam.
“We've had a lot of people change their tune in terms of negotiations. So my mailbox was full last night with a lot of new offers, a lot of new proposals,” Mr Bessent told CNBC.
Washington and Beijing had also previously agreed to lower their tariff rates on each other as part of a so-called trade truce.
Mr Trump has also threatened to impose another 10 per cent tariff on any country that aligns itself with the Brics group of emerging economies.
