Juncker’s remarks in Malta came a day after Theresa May, the U.K. prime minister, officially invoked Article 50 of the Lisbon treaty and triggered two years of negotiations that would lead to her country’s exit from the EU. The U.K. is the first country in the 28-member bloc to say it wants to leave. Juncker had not only warned against Brexit, as the U.K.’s exit is known, but labeled Britons who wanted to leave “deserters,” said the consequences of a Brexit would be a “catastrophe” for the U.K., said it owned the EU 60 billion pounds, and added “Britain’s example will make everyone realize that it’s not worth leaving.” All of which led even a British supporter of the U.K.’s continued membership of the EU to urge German Chancellor “Angela Merkel and whoever leads France … to … take Juncker and lock him in cell until the whole thing [Brexit] is over. He’s a menace.”

His critics may view him a “menace,” but Juncker, who was described in one profile as an “arch-pragmatist with a love of a drink and a dry sense of humor” is passionate about Europe. He was born in 1954 in a continent ravaged by World War II, and he spent his entire professional life in politics working to strengthen European integration, a utopian ideal just decades ago. The EU today may conjure up jokes, complaints about bureaucracy, and fears of a European superstate, but the EU has fostered unprecedented unity in an area engaged in war almost constantly through history until 1945.

It’s that vision of Europe that Juncker has tried to preserve. This month, he told European leaders, “It would do us all good if we simply stopped Brussels-bashing, EU-bashing,” and laid out his vision for the EU as being “about more than market, goods and money.” That view clashes with the one held by many Europeans, including politicians and parties that have made common cause with Trump, and have viewed his election as a boost to their own electoral prospects and as a win for populism against the elitist establishment that Juncker represents. Trump cheered Brexit, and appeared to suggest other EU members states will follow the U.K.’s lead. This prompted Juncker to comment in January, just before the American president’s inauguration, that Trump should not be “indirectly encouraging” countries to leave the EU. “We don’t go around calling on Ohio to pull out of the United States.” Indeed, he said he told U.S. Vice President Mike Pence that Trump’s alleged encouragement of other countries to emulate Brexit could result in a breakup of the EU and war in the Balkans. “If we leave them alone—Bosnia Herzegovina, Republika Srpska, Macedonia, Albania, all those countries—we will have war again,” he told the Financial Times last week, referring to the bloody wars in the 1990s that followed the breakup of Yugoslavia.

Juncker is scheduled to visit Washington this month. It’s unclear if he’ll meet with Trump, and his remarks to the FT suggested he didn’t really care. “They’re trying to fix it [a meeting], but he has other priorities,” he said. “By the way, he does not understand anything about Europe. He had Tusk [Donald Tusk, president of the European Council] on the phone and he thought it was me.”

It’s that quality that’s unlikely to endear him in Trump’s Washington. As a European official said of Juncker: He has “two fatal flaws—he has an opinion and he is not afraid to share it.”