NANTUCKET, United States (AFP) — President Joe Biden on Thursday warned against damaging relations with Canada and Mexico, after Donald Trump threatened to slap tariffs on both US neighbours when he takes office in January.

“I think it’s a counterproductive thing to do,” Biden told reporters when asked about his successor’s plan.

“The last thing we need to do is begin to screw up those relationships. I think we got them in a good place,” he said during a visit to a fire department in Nantucket, Massachusetts, where he is spending his last Thanksgiving holiday as president.

Trump sent jitters through global markets on Monday when he announced on social media that one of his first presidential actions would be to impose 25 per cent tariffs on Mexico and Canada — which share a free trade pact with the United States — and add a 10 per cent tariff on China.

Pledging that tariffs would only be removed from the US neighbours when illegal immigration and drug trafficking stop, Trump reaffirmed his intent to use trade as a cudgel against allies and rivals alike.

After expressing opposition to Trump’s threats in a letter, Mexican President Claudia Sheinbaum spoke by phone with the Republican president-elect on Wednesday.

Both leaders described the call positively, though there was disagreement in what had actually been discussed.

Trump claimed that Sheinbaum had agreed to “stop migration through Mexico and into the United States, effectively closing our southern border”.

The Mexican president quickly pointed out that she had only explained Mexico’s current “comprehensive strategy” on migration.

“Thanks to this, migrants and caravans are attended to before they reach the border,” she said on X.

“We reiterate that Mexico’s position is not to close borders but to build bridges between government and peoples,” she added.

When asked about the dispute at her daily press conference on Thursday, Sheinbaum said: “I can assure you… that we would never — we would not be capable — of proposing that we were going to close the border.”

The Mexican Government had warned that Trump’s tariffs would be met with retaliation, potentially endangering American jobs, with Sheinbaum’s economy minister saying it would be “a shot in the foot”.

Sheinbaum said Thursday that after her talks with Trump, “there is not going to be a potential tariff war”.

“The important thing was to address the approach he made,” she said, adding that she believed dialogue with Trump would be constructive.

Biden on Thursday also talked about the importance of maintaining a working relationship with China.

“We’ve set up a hotline between President Xi and myself, as well as our military, a direct line,” Biden said.