As President Trump seeks to wind down the war in Iran, the United States is facing not only economic fallout such as higher gas prices but also mounting geopolitical costs. Fresh disputes between Washington and NATO over the Middle East conflict are pushing European leaders to seriously consider a future in which the U.S. no longer leads the alliance.
Trump's decision to leave NATO in the dark before launching strikes on Iran — as well as his subsequent call for the alliance to assist in reopening the Strait of Hormuz — has inflamed tensions that had been simmering for months over the president's threats to seize control of NATO-linked Greenland and Canada, along with repeated suggestions that the United States might withdraw from the alliance entirely.
"Something fundamental has broken," says Ivo Daalder, a former U.S. ambassador to NATO under President Barack Obama. Trump, he says, doesn't believe America's security depends on the security of Europe — a position that defies decades of foreign policy logic going back to the end of World War II, when NATO was founded by the U.S., Canada and their European allies to provide a bulwark against Soviet aggression.
It has Europe and Canada increasingly asking an unthinkable question, Daalder says: Will the United States come to the aid of its NATO allies?
That anxiety is reshaping military planning, defense spending, procurement decisions and the future structure of the alliance itself. With that in mind, here are four signs that NATO's future is entering its most uncertain period since the Cold War.
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The United States announces plan to withdraw U.S. troops from Germany
Late last month, German Chancellor Friedrich Merz said publicly that the U.S. appeared to lack a clear exit strategy in Iran and that Tehran had "humiliated" Washington in peace talks. The comment drew a sharp response from Trump, who soon indicated that U.S. troop levels in Germany were under review.
This week, the Pentagon followed through, announcing plans to withdraw 5,000 U.S. service members — about 14% of the roughly 36,000 troops stationed in Germany, a presence that dates to the early Cold War.
In a statement to NPR last week, Pentagon spokesman Sean Parnell said Defense Secretary Pete Hegseth ordered the withdrawal, which reflects "a thorough review of the Department's force posture in Europe" and conditions on the ground.
The move comes as Berlin said that plans formulated during the Biden administration to deploy U.S.-made Tomahawk missiles to Germany might be shelved. Speaking about the Tomahawks on Monday, German Defense Minister Boris Pistorius said, "There are ideas, but no solution yet" on ways to fill such a gap. NPR reached out to the Pentagon requesting an update on the plans to deploy Tomahawks but received no immediate response.
While the drawdown is seen as largely symbolic, it underscores broader concerns about what it would mean if the United States took a definitive step back from NATO, as Trump has suggested, just as Russia poses the biggest threat to Europe since the end of the Cold War.
It follows Spain's refusal to allow the U.S. access to two joint military bases in southern Spain for use during the U.S.-Israel war in Iran. Trump has also publicly criticized Britain after its prime minister, Keir Starmer, publicly distanced the U.K. from America's Iran policy, declaring, "This is not our war." In an interview, Starmer also said he was "fed up" at the economic consequences wrought upon ordinary Britons "because of the actions of Putin or Trump across the world."
The tensions come at "not a great time, when Europe is still in the midst of its largest land war since World War II," says Seth Jones, president of the Defense and Security Department at the Center for Strategic and International Studies in Washington, D.C., referring to Ukraine.
The heated rhetoric has cooled somewhat recently. Britain and France are committing some resources to reopening the Strait of Hormuz. Speaking in a BBC interview last month, Starmer said the U.K. would not join the U.S. blockade of Iranian ports but does have a minesweeping capability that is "focused ... on getting the strait fully open." France is sending the aircraft carrier Charles de Gaulle to the Red Sea.
In an email to NPR, White House spokesperson Anna Kelly said: "President Trump has made his disappointment with NATO and other allies clear. Europe benefits tremendously from the tens of thousands of United States troops stationed in Europe — yet requests to use military bases in order to defend American interests were denied. The President has effectively restored America's standing on the world stage and strengthened relationships abroad — but he simultaneously will never allow the United States to be treated unfairly and taken advantage of by so-called 'allies.'"
The loss of trust is real
David Perry, president of the Canadian Global Affairs Institute, notes that NATO members' distrust of the U.S. tracks closely with Trump's presidency, particularly the amped-up "invade Greenland" and "annex Canada" rhetoric in his second term. Greenland, in particular, rose to the level of being "actionable," he says, noting that NATO was "doing military planning against a potential contingency involving the United States."
"That's an astonishing thing to say about allies in an alliance that's over three-quarters of a century old," he adds.
This week, Canadian Prime Minister Mark Carney became the first non-European leader to be invited to a meeting of the European Political Community. Speaking in Armenia at a summit on the future of Europe, Carney said the international order could be "rebuilt out of Europe." He added that Ottawa is interested in deepening relations with "reliable partners," a likely reference to how unreliable the U.S. has proved, according to Perry.
Perry says that anti-American attitudes in Canada are definitely on the rise since the start of Trump's second term and that politicians are feeling the pressure. That is true elsewhere as well.
"If you look at Germany, general favorability polls for America have just been plummeting," says Constanze Stelzenmüller, director of the Center on the United States and Europe at the Brookings Institution.
It will be hard to replace U.S. capabilities
Europe and Canada currently lack the capacity to credibly "go it alone" at the highest end of military operations. They field capable forces but are heavily reliant on the U.S. for long-range precision-strike capability, strategic lift to move troops and matériel to the battlefield, and advanced intelligence, surveillance and reconnaissance assets, according to Stelzenmüller.
"For the critical purpose of supporting Ukraine, the U.S. possesses capabilities that we have not yet been able to produce," she says.
She says there was a sense as recently as last year that the U.S.-NATO relationship was solid enough that "we could still rely for quite a while longer on the U.S. nuclear deterrent and a steady flow of U.S. weaponry for us to buy and then give to Ukraine." That's no longer the case, she says. "The scope of what we need to produce ourselves has become much broader, and the timeline to do it in is much shorter."
NATO leaders are aware that acquiring these capabilities is a vital but time-consuming task, according to Balkan Devlen, a senior fellow at the Macdonald-Laurier Institute, an independent think tank based in Ottawa.
Devlen estimates that it will take between five and 10 years to develop these capabilities, leaving a "vulnerability gap" that Russia could exploit in the meantime. "You cannot just 'Amazon next day order' these things," he says.
As a result, says Jim Townsend, a former U.S. deputy assistant secretary of defense for European and NATO policy, "There is some anger now being expressed, because not only is the U.S. stepping away, but we are dumping this on the allies without any transition period.
Trump has repeatedly criticized NATO allies for failing to spend enough on their own defense. In recent years, however, member states have sharply increased military outlays in line with a 2014 pledge to spend at least 2% of gross domestic product on defense. Several countries — including Poland, Lithuania, Latvia, Estonia and Denmark — now meet or exceed that benchmark, with some approaching or surpassing U.S. defense spending as a share of their economies. At last year's NATO summit, members agreed to a new target of 5% of GDP by 2035.
"They're going to have to translate that into combat capability," to include spending on ground forces, says Jones, of the Center for Strategic and International Studies.
The discussions about burden sharing in the alliance are nothing new, dating back to long before Trump. But the irony is that the very pressure Trump has applied — combined with the shock of Russian President Vladimir Putin's full-scale invasion of Ukraine — helped drive the long-delayed surge in allied defense spending after years of lagging behind.
With Russia at NATO's doorstep in Ukraine, internal squabbling coming from the U.S. means the alliance is facing "a two-front challenge, east and west," according to Douglas Lute, who succeeded Daalder as U.S. ambassador to NATO under Obama.
"They've got to buy some insurance against longer-standing trends in American politics," he says.
"A stronger European pillar of NATO is good for America," Lute, a retired Army three-star general, says. "The problem is that if they step up because they can't trust us, that at the same time is not good for America."
There is no obvious replacement for the U.S.
In the decades after the formation of NATO in 1949, the U.S. played the lead role, helping rally Western Europe to its own defense even as the region was still trying to rebuild from the devastation of World War II. The U.S., Canada and 10 European nations, including Belgium, the United Kingdom, France and Italy, originally made up NATO. West Germany was added in 1955, and a reunified Germany in 1990. Today, many of the alliance's 32 member states are drawn from the now-defunct Soviet-controlled Warsaw Pact counterpart to NATO.
"America was not just a provider of military capabilities but also the political balancer," Stelzenmüller says.
Last month, Germany's Pistorius unveiled a sweeping new defense plan signaling that Berlin is preparing to assume a far larger role within NATO. The first comprehensive military doctrine issued by Germany since the Cold War identifies Russia as the main threat to European security, warning that Moscow is "laying the groundwork for a military attack on NATO member states." The plan reiterates Germany's ambition to build Europe's strongest conventional military by the mid-2030s, with a force of roughly 460,000 troops — including more than 200,000 active-duty personnel — aimed largely at reinforcing NATO's eastern flank.
Lute acknowledges that Germany in particular is "stepping up in a significant way" but sees the future of NATO leadership as a collective effort. Germany, France and the U.K. are all likely to pick up the mantle left by a retreating U.S., he says. "To the extent that the three of them can come together — and increasingly be joined by Poland — I think that set of the four strongest, largest, most vigorous NATO allies has the most potential."
The experts NPR spoke to do not think Trump's threats to pull out of the alliance will come to fruition. In any case, it's a decision that cannot be made unilaterally, per a law enacted by Congress in 2023. "I think that there will definitely be a NATO, but it's going to be a European NATO, if you will," Townsend says. "It won't be NATO guided by the United States."
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