President Donald Trump said on Thursday that larger tariffs could be placed on the European Union and Canada if they both work together "to do economic harm to the USA."

"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," he said in a post on Truth Social.

On Wednesday, Trump unveiled a 25% tariff on imported vehicles, expanding a global trade war and prompting criticism and threats of retaliation from affected U.S. allies.

European Commission President Ursula von der Leyen described the move as "bad for businesses, worse for consumers," while Canadian Prime Minister Mark Carney labeled the tariffs a "direct attack" on Canadian workers and said retaliatory measures were being considered.

The new levies on cars and light trucks will take effect on April 3, the day after Trump plans to announce reciprocal tariffs aimed at the countries responsible for the bulk of the U.S. trade deficit. They come on top of duties already introduced on steel and aluminum, and on goods from Mexico, Canada and China.

The EU has said it will delay its first set of counter-measures to mid-April, including a 50% tariff on U.S. bourbon. In response, Trump threatened to slap a 200% tariff on all wines and other alcoholic products from the EU if the bloc went ahead with this.