US President Donald Trump rekindled his trade war with the European Union on Friday by threatening 50 percent tariffs, as Brussels reacted with a call for "respect."

Trump also unleashed a broadside against smartphone makers including US tech giant Apple, threatening them with new duties of 25 percent if they do not move production to the United States.

Stock markets fell as the Republican's comments fueled fears of global economic disruption, after a relative lull in recent days after Trump reached deals with China and Britain.

Trump first raised the issue of EU tariffs in an early morning post on his Truth Social network. 

"Our discussions with them are going nowhere!" Trump said. "Therefore, I am recommending a straight 50 percent Tariff on the European Union, starting on 1 June 2025."

He doubled down later in the day, telling reporters in the Oval Office that there was nothing the 27-nation bloc could do to change his mind.

"I'm not looking for a deal. I mean, we've set the deal. It's at 50 percent," Trump said. "They haven't treated our country properly. They banded together to take advantage of us."

Billionaire property tycoon Trump, 78, also denied that his tariffs would hurt American businesses.

"They’re not hurting, they're helping," he said.

Trump's new tariffs would, if imposed, dramatically raise Washington's current baseline levy of 10 percent, and fuel simmering tensions between the world's biggest economy and its largest trading bloc.

The EU's trade chief said the bloc would work for a trade deal with Washington based on "respect" not "threats."

"The EU's fully engaged, committed to securing a deal that works for both," trade commissioner Maros Sefcovic posted on X, after a previously planned call with US Trade Representative Jamieson Greer and Commerce Secretary Howard Lutnick.

In a separate message posted Friday that also unnerved markets, Trump blasted Apple boss Tim Cook for failing to move iPhone production to the United States despite repeated requests.

Trump said he had "long ago informed Tim Cook of Apple that I expect their iPhones that will be sold in the United States of America will be manufactured and built in the United States, not India, or anyplace else." 

"If that is not the case, a Tariff of at least 25% must be paid by Apple to the US"

Trump later stepped up his threats, saying he would hit all smartphones not made in the country.

"It would be also Samsung and anybody that makes that product, otherwise it wouldn't be fair," Trump told reporters, adding that the new tariffs would come into effect from the end of June.

Market worries

Trump imposed sweeping tariffs on most of the world on what he called "Liberation Day" on April 2, with a baseline 10 percent plus steeper duties including a 20 percent levy on the EU.

Markets were thrown into turmoil but calmed after he paused the bigger tariffs for 90 days.

Trump has since claimed some early successes in deals struck with Britain and with China, the world's second biggest economy.

But talks with the EU have failed to make much progress, with Brussels recently threatening to hit US goods worth nearly 100 billion euros ($113 billion) with tariffs if it does not lower the duties on European goods.

US Treasury Secretary Scott Bessent told Bloomberg Television on Friday the lower 10 percent tariff rate was "contingent on countries or trading blocs coming and negotiating in good faith."

Wall Street's main indexes were all down around one percent two hours into trading, with the tech-heavy Nasdaq at one stage losing 1.5 percent before rallying while Apple shares sank 2.5 percent.

Paris and Frankfurt ended with losses of around 1.5 percent, while London's FTSE 100, which initially rose, also ended in the red.

"The administration had kind of hinted that they were considering imposing reciprocal tariffs on countries that weren't negotiating in good faith," Barclays senior US economist Jonathan Millar told AFP. 

by Daniel AVIS and Danny KEMP