WASHINGTON-President Trump said Wednesday that allowing Canada to become an associate member of the European Union could be a "hostile act" and threatened additional tariffs on European countries.

The president said that the proposition was "laughable" and described Canada as a "terrible trade partner." The comments came after the EU's top official said she would work to make Canada the bloc's first associate member. In a speech at the European Parliament with Canadian Prime Minister Mark Carney in attendance, European Commission President Ursula von der Leyen said Europe needed to tighten its cooperation with like-minded democracies, in particular Canada.

"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," Trump said, responding to a question about Canada possibly becoming an associate member of the EU. "So, if they do that, if Europe does that, with a bad intention-if it's a good intention, that's fine-if it's a bad intention, we'll put very heavy tariffs on Europe."

Relations between the U.S. and Canada, which are close allies and trading partners, have grown increasingly tense in recent weeks. Trump has signed orders to ban the importation of many dairy products, alcoholic beverages and motorcycles from Canada in the coming weeks, a retaliation for Canadian tariffs that took effect. He also modified the scope of some existing 50% tariffs on Canada, removing levies on cement, road salt and some hospital products, while imposing 50% levies on other products including some all-terrain vehicles, boats and cheeses.

The U.S. and Canada nearly came to a trade agreement in late August, but the talks fell apart at the last minute. Trump subsequently signed an executive order to rename Lake Ontario, located along the U.S.- Canada border, as "Lake America."

The Wall Street Journal recently reported that Canadian and European officials were discussing the prospect of associate membership-a new category of relationship with the bloc. European and Canadian officials have said that while full membership of the EU isn't an option, they want the closest possible relationship.