US President Donald Trump unveiled higher tariffs for Japan, South Korea and a dozen other countries in a push for new trade deals Monday, but extended the deadline for the steeper levies to kick in until August.

Trump issued similar letters to countries including Indonesia, Bangladesh, Thailand, South Africa and Malaysia, saying he would slap duties on their products ranging from 25% to 40%.

These mark a step up from the 10% levy the president earlier imposed on almost all trading partners.

But the starting date of August 1 marks a delay in Trump´s reimposition of higher duties, originally due Wednesday.

In near-identically worded letters to Japanese and South Korean leaders, Trump said US tariff hikes to 25% came as their trading relationships with Washington were "unfortunately, far from Reciprocal."

He warned of further escalation if there was retaliation against the levies.

But the president said he was ready to lower the new levels if partners changed their trade policies: "We will, perhaps, consider an adjustment to this letter."

Japan´s Prime Minister Shigeru Ishiba said Sunday that he "won´t easily compromise" in trade talks with Washington.

Trump originally announced sweeping tariffs on world economies during what he called "Liberation Day" on April 2, claiming the United States was being "ripped off."

Amid market turmoil, he then suspended higher duties affecting dozens of economies for 90 days, a deadline that would have expired Wednesday.

On Monday, Trump signed an order formally extending the Wednesday deadline, postponing it to August 1.

With the delay, White House Press Secretary Karoline Leavitt noted that Trump would set out the "reciprocal tariff rate" for partners in the coming month as negotiations continue.

According to letters posted to Trump's Truth Social platform, products from Indonesia will face a 32% tariff, while the level for Bangladesh is 35% and Thailand, 36%.

Most countries receiving letters so far had duties similar or unchanged from threatened rates in April, although some like Laos and Cambodia see notably lower levels.

While the Trump administration had signalled hopes of striking dozens of deals by July, there have been limited results so far.

Washington has unveiled pacts with only Britain and Vietnam, while the United States and China agreed to temporarily lower tariff levels on each other´s products that earlier reached three digits.

Change their tune

Asked why Trump opted to start with South Korea, Leavitt said: "It´s the President´s prerogative, and those are the countries he chose."

"This announcement will send a chilling message to others," said Asia Society Policy Institute Vice President Wendy Cutler, referring to Trump´s initial letters to Tokyo and Seoul.

"Both have been close partners on economic security matters," she said, adding that companies from Japan and South Korea have made "significant manufacturing investments in the US in recent years."

US Treasury Secretary Scott Bessent said Monday that there would be more deals coming up: "We are going to have several announcements in the next 48 hours."

"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," Bessent told CNBC.

He added that he would meet with his Chinese counterpart in the coming weeks.

Both sides have so far held high-level talks in Geneva and London. But Washington and Beijing´s pause on higher tit-for-tat tariffs is due to expire in mid-August.

Major US stock indexes fell from records Monday on Trump's fresh threats. The Nasdaq tumbled 0.9% and the S&P 500 lost 0.8%.

Trump has also threatened another 10% tariff on countries aligning themselves with the emerging BRICS nations, accusing them of "anti-American policies" after they slammed his duties at a summit.

But partners are still rushing to avert Trump's tariffs altogether.

The European Commission said EU chief Ursula von der Leyen had a "good exchange" with Trump on trade when the pair spoke Sunday.