European leaders who scrambled for a year to figure out how to deal with an emboldened American president in his second term edged closer to saying “no,” or something diplomatically like it, to his disregard for international law and his demands for their territory. Trump’s vow to take over Greenland and punish any country that resists, seems to have been the crucible.

“Red lines” were deemed to have been crossed this year when Trump abruptly revived his demand that the United States “absolutely” must rule Greenland, the semiautonomous region that is part of NATO ally Denmark. That pushed even the most mild-mannered diplomats to issue sharp warnings against Trump, whom they had flattered withroyal treatment and fawning praise.

“Britain will not yield” its support for Greenland’s sovereignty, British Prime Minister Keir Starmer said. Several of the continent’s leaders said “Europe will not be blackmailed” over Greenland.

“Threats have no place among allies,” said Norwegian Prime Minister Jonas Gahr Støre.

The tough diplomatic talk around the showdown last week in Davos, Switzerland, was not the only factor pressuring Trump. U.S. congressional elections are approaching in November amid a sinking stock market and wilting approval ratings. European leaders also are not the first to stand in Trump’s way during his second term — see Federal Reserve Chair Jerome Powell.

But the dramatic turnabout among Europe’s elite, from “appeasing” Trump to defying him, offers clues in the ongoing effort among some nations of how to say “no” to a president who hates hearing it and is known to retaliate.

“We want a piece of ice for world protection, and they won’t give it,” Trump told his audience at the World Economic Forum. “You can say yes, and we will be very appreciative. Or you can say no, and we will remember.”

Lesson 1: Speak as one

In recent days, Europe offered abundant refusals to go along with Trump, from his Greenland demand and joining his new Board of Peace and even to what Canada’s Mark Carney called the “fiction” that the alliance functions for the benefit of any country more than the most powerful. The moment marked a unity among European leaders that they had struggled to achieve for a year.

“When Europe is not divided, when we stand together and when we are clear and strong also in our willingness to stand up for ourselves, then the results will show,” Danish Prime Minister Mette Frederiksen said. “I think we have learned something.”

Federiksen herself exemplified the learning curve. A year ago, she and other leaders were on their heels and mostly responding to the Trump administration. She found it necessary to tell reporters in February 2025, “We are not a bad ally,” after Vice President JD Vance had said Denmark was “not being a good ally.”

Trump is transactional. He has little use for diplomacy and no “need (for) international law,” he told The New York Times this month. Therein lay the disconnect between typically collaborative European leaders and the Republican president when he blazed back into the White House saying he wanted the U.S. to take over Greenland, Panama and perhaps even Canada.

“In Trump’s first term, Europe didn’t know what to expect and tried to deal with him by using the old rules of diplomacy, with the expectation that, if they kept talking to him in measured terms, that he would change his behavior and move into the club,” said Mark Shanahan, associate professor of political engagement at the University of Surrey,.

“It’s very hard for other leaders who deal with each other through the niceties of a rules-based system and diplomatic conversation,” Shanahan said. “It is hard for them to change.”

Five months after Trump’s inauguration last year, with his Greenland threat in the air, European leaders had gotten their heads around Trump management enough to pull off a meeting of NATO nations in the Netherlands. NATO members agreed to contribute more and widely gave Trump credit for forcing them to modernize.

Secretary-General Mark Rutte, known as the coalition’s “Trump whisperer,” likened the president’s role quieting the Iran-Israel war to a “daddy” intervening in a schoolyard brawl.

Lesson 2: Consider saying no — and make choices accordingly

Traditional diplomacy exists to preserve possibilities of working together. That often means avoiding saying a flat “no” if possible. But Trump’s Greenland gambit was so stark a threat from one NATO member to another that Greenland’s prime minister actually said the word.

“Enough,” Jens-Frederik Nielsen said in a statement shortly after Trump’s remarks Jan. 5. “No more pressure. No more hints. No more fantasies about annexation.”

That played a part in setting the tone. Denmark’s leader said any such invasion of Greenland would mark the end of NATO and urged alliance members to take the threat seriously.

They did, issuing statement after statement rejecting the renewed threat. Trump responded last weekend from his golf course in Florida with a threat to charge a 10% import tax within a month on goods from eight European nations — Denmark, Norway, Sweden, France, Germany, the United Kingdom, the Netherlands and Finland. The rate, he wrote, would climb to 25% on June 1 if no deal was in place for “the Complete and Total purchase of Greenland” by the United States.

Lesson 3: Reject Trump’s big-power paradigm

Trump’s fighting words lit a fire among leaders arriving in Davos. But they seemed to recognize, too, that the wider Trump world left him vulnerable.

“Trump was in a fairly weak position because he has a lot of other looming problems going on,” domestically, including an upcoming U.S. Supreme Court decision on his tariffs and a backlash to immigration raids in Minnesota, said Duncan Snidal, professor emeritus of international relations at Oxford University and the University of Chicago.

Canada’s Carney said no by reframing the question not as being about Greenland, but about whether it was time for European countries to build power together against a “bully” — and his answer was yes.

Without naming the U.S. or Trump, Carney spoke bluntly: Europe, he said, should reject the big power’s “coercion” and “exploitation.” It was time to accept, he said, that a “rupture” in the alliance, not a transition, had occurred.

Unsaid, Snidel pointed out, was that the rupture was very new, and though it might be difficult to repair in the future, doing so under adjusted rules remains in U.S. and European interests beyond Trump’s presidency. “It’s too good a deal for all of them not to,” Snidel said.

Lesson 4: Exercise caution

Before Trump stepped away from the podium in Davos, he had begun to back down.

He canceled his threat to use “force” to take over Greenland. Not long after, he reversed himself fully, announcing “the framework” for a deal that would make his tariff threat unnecessary.

Trump told Fox Business that “we’re going to have total access to Greenland,” under the “framework,” without divulging what that might mean.

Frederiksen hit the warning button again. In a statement, she said, “We cannot negotiate on our sovereignty.”

In other words: “No.”