EU leaders meeting in Brussels on Monday cautioned that no one would benefit from a trade war with the United States, warning they would respond if President Donald Trump followed through on his tariff threats.

French President Emmanuel Macron urged the European Union to demonstrate strength, stating, “If we are attacked in terms of trade, Europe—as a true power—will have to stand up for itself.”

The leaders of the EU’s 27 nations convened alongside Britain’s prime minister and NATO’s chief to discuss European defense amid rising tensions with Russia. However, their talks were overshadowed by Trump’s latest tariffs on Canada, Mexico, and China, with the U.S. president hinting that the EU could be next.

Poland’s Prime Minister Donald Tusk, whose country currently holds the EU presidency, called for efforts to prevent a “totally unnecessary and stupid” trade war. German Chancellor Olaf Scholz echoed the concerns, saying a trade dispute would be harmful for both sides, while EU foreign policy chief Kaja Kallas stressed, “There are no winners in trade wars.”

The European Commission has vowed to retaliate “firmly” if Trump targets the bloc, denouncing tariffs as disruptive and inflationary. Brussels had initially sought to avoid confrontation through negotiations but is now exploring alternative trade partnerships, recently strengthening a deal with Mexico and reviving talks on a free trade agreement with Malaysia.

In a late-night call, European Council chief Antonio Costa and Canadian Prime Minister Justin Trudeau reaffirmed their commitment to EU-Canada ties.

The situation recalls Trump’s first term in 2018, when he imposed tariffs on European steel and aluminum, prompting the EU to hit back with its own countermeasures. Now, with Trump back in office, fears of another trade conflict are growing.