US President Donald Trump continues to escalate his trade war. He says he will slap 25 percent tariffs on auto imports starting April 3, and his move has sparked sharp reactions around the world.

White House Press Secretary Karoline Leavitt praised the tariffs on Thursday. She said they are a "big deal" for American autoworkers.

But outside the US, Trump's latest salvo came in for some tough criticism.

Canadian Prime Minister Mark Carney told reporters Thursday that he is ready to defend his country. He said, "We will fight the US tariffs with retaliatory trade actions of our own that will have maximum impact in the United States and minimum impacts here in Canada."

German Chancellor Olaf Scholz said, "the decision is wrong" and that US is taking a path that "will only end in losers" because tariffs and isolation hurt prosperity for everyone.

Japanese Prime Minister Ishiba Shigeru said that his country will carefully consider its response, and that all options are on the table, including countermeasures.

Trump has not changed his stance. He took to social media on Thursday to warn his trading partners: "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."

But the White House said it will exempt auto parts under the US-Mexico-Canada Agreement, or USMCA, until a process to identify non-US content is set up. The three neighbors have highly integrated car industries and parts flow back and forth across the borders.