President Donald Trump announced on Thursday that his administration would impose large tariffs on aluminum and other metals on three of the U.S.’s closest allies: the European Union, Canada and Mexico.

U.S. Levies Tariffs On EU, Canada And Mexico

The move has sparked concern this will escalate a trade war, especially after Canadian Prime Minister Justin Trudeau and top European officials both heavily criticized the White House’s decision.

Canada, Mexico and the EU will reportedly face 10 percent tariffs on aluminum and 25 percent tariffs on steel, and leaders from the countries affected quickly responded by warning they would likely retaliate.

“These tariffs are totally unacceptable,” said Trudeau. “Canada is a secure supplier of aluminum and steel to the U.S. defense industry, putting aluminum in American planes and steel in American tanks.”

Trudeau added that the Trump administration’s decision makes it seem like the U.S. views Canada as a “national security threat,” an idea he called “inconceivable.”

French President Emmanuel Macron — who recently visited the White House and was regarded as someone Trump had a positive relationship with — also condemned the U.S.’s move.

Macron called the decision “illegal” and a “mistake,” and cited brash trade and other economic decisions as one of the major factors that led to World War II.

“Economic nationalism leads to war,” said Macron. “This is exactly what happened in the 1930s.”

According to The New York Times, German Chancellor Angela Merkel also said the tariffs are “illegal.”

Among the retaliatory measures the EU reportedly threatened was countering with tariffs on American goods like Kentucky bourbon, motorcycles and blue jeans.

Mexican officials said the U.S.’s tariffs would “distort international trade” and also warned it would respond with its own set of tariffs on U.S. imports like apples, cheeses, pork and flat steel.

Trump insisted that Canada “open their markets and take down trade barriers.” The president has reportedly been trying to use the levying of tariffs as a way to get Canada and Mexico to discuss the possibility of renegotiating the long-standing North American Free Trade Agreement with the U.S. Trump has repeatedly slammed NAFTA as a “bad deal” that has not benefited the U.S. over the last few years.

The Trump administration has also come under fire for risking a trade war with other countries like China, whom the president has long accused of “dumping” and currency manipulation. Despite touting an “America First” platform that includes a promise to help protect U.S. workers from what he views as unfair international competition, Trump vowed earlier this spring to help save Chinese jobs, like those held by workers at electronics firm ZTE. In March, Trump levied tariffs on several nations but initially said he would allow temporary exemptions for Mexico and Canada. He also added the EU to that listed, but only on the condition that the EU re-negotiate decisions on quotas and other trade restrictions.

Theresa May, the British Prime Minister, said the U.K. is “deeply disappointed” in the Trump administration’s decision on tariffs.