Trump, speaking to reporters at the White House a day after his inauguration, also warned the European Union it could face stiff levies, while taking aim once again at Beijing over fentanyl trafficking.

"They treat us very, very badly. So they're going to be in for tariffs," Trump said of the EU. "You can't get fairness unless you do that."

A day earlier, the new president accused the bloc of not importing enough American products, saying he would "straighten that out" by imposing tariffs or by urging for more oil and gas purchases.

On China, Trump reiterated his threat Tuesday to impose a 10 percent duty, saying it was "based on the fact that they're sending fentanyl to Mexico and Canada".

When asked how soon they could be put in place, he said: "Probably February 1st is the date we're looking at."

That is the same date he had previously said he could impose 25 percent tariffs on Canada and Mexico, having accused them of failing to stop illegal immigration and fentanyl trafficking into the United States.

Mexico, Canada and China are leading sources of US imports, according to official trade data.

Beijing on Wednesday vowed to defend its "national interests" in response to Trump's threats.

"We have always believed that there are no winners in a trade war or a tariff war," foreign ministry spokeswoman Mao Ning said.

She added that Beijing was "willing to maintain communication with the US, properly handle differences, expand mutually beneficial cooperation, and promote the stable, healthy, and sustainable development of China-US relations".

- 'Common interests' -

The Trump White House imposed tariffs on imports from China during his first term, citing alleged unfair practices by Beijing.

His successor Joe Biden kept up the pressure with sweeping rules aimed at restricting Chinese access to high-tech chips.

Trump threatened to go even further during his election campaign, vowing even higher tariffs if he won another term in office.

China's economy remains heavily reliant on exports to drive growth despite official efforts to raise domestic consumption.

The EU's economy commissioner also vowed this week that the bloc stood ready to defend its interests.

Speaking at an annual economic gathering in Davos, Switzerland, EU chief Ursula von der Leyen declared that Europe was ready to negotiate with Trump, while maintaining that Washington remained an important partner.

The EU's "first priority will be to engage early, discuss common interests, and be ready to negotiate" with the president, she said.

"We will be pragmatic, but we will always stand by our principles, to protect our interests and uphold our values."

Trump on Monday vowed an immediate overhaul of the US trade system -- promising to "tariff and tax foreign countries to enrich our citizens".

He signed an order directing agencies to study a range of trade issues including deficits, unfair practices and currency manipulation.

The investigations could pave the way for further duties.

Europeans are fretting the most about Trump's return, while countries from Brazil to China and India to Turkey believe he will be good for their countries and global peace, according to a recent survey from the European Council on Foreign Relations.

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