Trump ramped up a global trade war as he imposed sweeping levies on imports into the United States on Wednesday, sparking worries about what the implications might mean for workers and businesses.

"I can't eat or sleep well because I keep worrying about losing my job," said Cao Thi Dieu, who helps make shoes for Western brands such as Nike and Adidas at a factory in Ho Chi Minh City.

Vietnam was hammered with huge tariffs of 46 percent as part of Trump's global trade blitz, which sent shares tumbling more than seven percent in Hanoi on Thursday.

Dieu, 38, feared the tariffs would impact the job she has been doing for two decades.

"How will I manage if I lose my job? How will I continue earning money each month to take care of my two children's education?" she said.

"I only want to stay in the shoe manufacturing job because I don't know how to do other work."

Erik Hon, 45, a director at a financial technology firm in Singapore, thought the tariffs would drive up global inflation.

"It is dangerous for everyone to have the most powerful country in the world going back to isolationism and trying to tame (a) China that is inevitably going to take over its world leadership position," he added.

Alicia Garcia-Herrero, chief economist for Asia Pacific at investment managers Natixis in Hong Kong, warned the tariffs could backfire.

"The largest loser is the US, because everybody's being taxed so there's no escape for higher inflation," she said.

- 'Worst-case scenario' -

Chrissy Chan, 48, a business owner in Malaysia, told AFP she was worried it would cost her more to travel to the United States to visit her family.

But she said the tariff rates "do not make sense to me... I won't be surprised if the Trump admin does another backpedal".

Chin Chee Seong, president of the SME (small and medium enterprises) Association of Malaysia said the higher tariffs on other countries might give Malaysian firms a competitive advantage.

However, "we import a lot of IT products from the US", he told AFP.

"If we impose a reciprocal tariff, the end user here will pay more. We will suffer. It works both ways."

Taiwan had sought to avoid Trump's levies by pledging increased investment in the United States, more purchases of US energy, and greater defence spending.

But Trump unleashed a hefty 32 percent levy on Taiwanese imports, and while the island's all-important semiconductor shipments were excluded, Taipei described the move as "unfair".

"The 32 percent really came as a surprise and I think our government was caught off guard," said Jason Hsu, senior fellow at the Hudson Institute think-tank and a former legislator in Taiwan for the opposition Kuomintang party.

"The implications are actually pretty big. I think the government has to think deeply about how to deal with Trump in the next four years with a completely new mindset."

Andrew Kam Jia Yi, an associate professor at the National University of Malaysia, expected Taiwan to lobby for more exemptions.

Trump "gives you the worst-case scenario then batters you down to a deal that you might not want but seems more reasonable than the original threat", he said.

burs-rjm/dan