US President Donald Trump threatened on Wednesday to cut trade ties with the EU after European Commission President Ursula von der Leyen proposed making Canada its first associate member.

"I think it's laughable," Trump told reporters when asked about the suggestion put forward by von der Leyen.

"If they do that, if I think it's at all a hostile act, I will put very serious tariffs or stop trading with Europe, on many things," he added.

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Trump said, "If it's a good intention, that's fine. If it's a bad intention, we'll put very heavy tariffs on Europe, which is a possibility."

In her annual State of the Union address to the European Parliament in Strasbourg on Wednesday, von der Leyen said the EU and Canada would seek to upgrade their ties from the Comprehensive Economic and Trade Agreement (CETA) to an "Alliance for the Future," covering manufacturing, technology, defense, the Arctic, energy, critical minerals and artificial intelligence.

"I would like to work with you on opening the door for Canada to be the first associate member of the EU," she told Canadian Prime Minister Mark Carney, who attended the address.

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The EU chief said she wanted to bring the relationship with Canada to "the highest level possible."