President Donald Trump on Thursday cautioned European countries against taking sides with Canada in the trade war.

The president warned that any action harming the U.S. economy would have repercussions.

Trump wrote on Truth Social: “If the European Union works with Canada in order to do economic harm to the USA, large-scale tariffs, far larger than currently planned, will be placed on them both in order to protect the best friend that each of those two countries has ever had!”

On Wednesday, Trump imposed a 25 percent tariff on imported vehicles, in addition to previously announced tariffs and reciprocal tariffs set to take effect on April 2.

The trade war has led to declining fortunes in the U.S. stock market and heightened global trade tensions as countries plan their next moves.

European Commission President Ursula von der Leyen stated that the new tariff on vehicles was “bad for businesses, worse for consumers.”

Canadian Prime Minister Mark Carney also criticized the action, describing it as a “direct attack” on workers in his country and threatening retaliation.

Trump threatens Canada, Europe with ‘large scale tariffs’