President Trump on Thursday threatened to impose larger tariffs on the European Union and Canada if they team up against the U.S., as an escalating trade war with the two allies continues.

“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!” Trump wrote on Truth Social early Thursday morning.

The threat comes a day after Trump announced that he will impose a 25 percent tariff on foreign-made vehicle imports, which will hit countries like Germany particularly hard.

European automakers criticized the move, arguing it will hurt U.S. manufacturing while the nations are already impacted by Trump’s steel and aluminum tariffs on trading partners.

The president has also teased reciprocal tariffs set to take effect April 2 — which the president has called “liberation day” — which will hit trading partners with the same tariffs they levy on the U.S.

Earlier this month, Trump announced broad tariffs on Canadian and Mexican imports and a one-month delay for auto parts covered under the U.S.-Mexico-Canada trade agreement, which is set to expire next week.