Two months ago, when President Trump was threatening to annex Greenland, I spoke with Danish and other European officials who warned of lasting damage to the system of alliances that the United States created after the Second World War, above all NATO.At the time, this seemed like a theoretical proposition. Denmark and other allies had come to the aid of the United States after the September 11 attacks, sending soldiers to fight in the American-led war in Afghanistan; these same countries, officials and experts hypothesized, might be less inclined to help in the future. But the possibility that the United States would actually require European assistance, especially in the Middle East, appeared faint. After all, Trump had promised to curtail military adventures, in order to refocus on American interests in the Western Hemisphere.The decision to wage war against Iran changed all that. Despite his earlier claims that the American military had already vanquished Iran and didn’t need partners to join the fight, Trump is now actively soliciting the help of other countries to reopen shipping lanes. And, sure enough, allies that once might have been eager to assist the United States in an area of mutual concern are reacting with, at best, a shrug—and in some cases with outright contempt.As oil prices spike, Trump has called on a wide range of countries to assist in reopening the Strait of Hormuz, normally the passageway for a fifth of global oil output. Among the objects of his entreaties are China, Japan, South Korea, and Australia. “I’m demanding that these countries come in and protect their own territory, because it is their territory,” Trump told reporters aboard Air Force One over the weekend. “It’s the place from which they get their energy.”True to form, he has saved some of his most belligerent comments for European partners. He named France and Britain in a Truth Social post over the weekend, insisting that “Many Countries” will be sending “War Ships” to help reopen the shipping lane. (No countries have announced any such plans.) He then told the Financial Times in an interview that there would be consequences for a failure to comply with his demands. “If there’s no response or if it’s a negative response, I think it will be very bad for the future of NATO.” In answer to a question about what he had in mind, a White House spokesperson pointed to additional comments the president made today that disparaged NATO. “We were going to protect them, but I always said, when in need, they don’t protect us,” he told reporters. “Now this is a need.”It turns out that American bullying has consequences. “We’re now seeing the theory in practice,” Rasmus Sinding Søndergaard, a specialist in U.S. foreign policy at the Danish Institute for International Studies, told me. “Does the feeling of being poorly treated by the United States have any sort of consequence for European willingness to show up and help?”In the past, Denmark and other European countries that viewed good relations with Washington as the foundation of their security would have been more willing to assist “even if they weren’t on board with the military mission per se,” Søndergaard said. “It’s pretty clear this is not the case anymore.” Proof of that came last night, when Denmark’s prime minister, Mette Frederiksen, gave a forthright answer to a question in a televised debate about whether she could still call the United States her country’s most important ally. “No, I can’t do that anymore,” she said, instead pointing to Europe, especially other Nordic countries, as well as Canada.[Read: Denmark’s army chief says he’s ready to defend Greenland]This recalibration has practical effects. During the Biden administration, in 2024, Denmark sent a frigate to the Red Sea as part of an American-led coalition to guarantee the security of maritime traffic in the face of attacks by Yemen’s Houthi militants. Denmark, home to the shipping giant Maersk, has significant interest, as well as expertise, in global shipping and logistics. But today, the Danish foreign minister, Lars Løkke Rasmussen, was guarded when discussing the possibility of backing U.S. efforts in the Strait of Hormuz, telling reporters that there should be a Europe-wide response as he suggested, elliptically, that Denmark would “keep an open mind.”Other countries have been unequivocal. Germany, which is in the midst of a rapid buildup of its military capabilities, ruled out sending forces to the region. “This is not our war; we did not start it,” the defense minister, Boris Pistorius, said at a news conference today. “We want diplomatic solutions and a swift end to the conflict, but sending more warships to the region will likely not help achieve that.”Germany’s position reflects a pragmatic response to a pattern of U.S. behavior. Roderich Kiesewetter, a member of the foreign-affairs committee in the German Parliament, ticked through the blows with me: downgrading Europe’s importance in annual national-security and defense strategies, dialing back support for Ukraine, and delivering a boost to the Kremlin’s war economy by lifting some sanctions on Russian oil. All of this, naturally, has repercussions. “It damages the transatlantic relationship and it explains the reluctance to join a difficult war,” Kiesewetter told me today. “We do not see Trump as a trustworthy ally anymore.”Trump may end up getting the support he craves in the Strait of Hormuz. British Prime Minister Keir Starmer said at a news conference today that his government was working with allies on a plan to reopen the sea passage, given the economic exigencies, while emphasizing, “We will not be drawn into the wider war.”[Read: Trump casually denigrates NATO’s war dead]No matter when the oil resumes flowing, this chapter in the broader Iran saga already has a clear conclusion. European countries have adapted to Trump’s transactional, and often fickle, approach to foreign policy. They will make decisions on the global stage based on shrewd assessments of their own interests, not magnanimity toward the United States. And perhaps that’s a good thing, said Søndergaard. “One could argue that the U.S. may be well served by allies that are willing to give critical feedback instead of a knee-jerk ‘Yes, sir’ reaction.” You can only kick a dog so many times before it bites back. Trump, who is the first president since Andrew Johnson not to have a pet in the White House, is learning the truth of this proverb.