Trump’s pressure on NATO is reshaping Europe’s defenses. Will it break the alliance?
The White House has said the six-month review will “ensure irreversible momentum toward a European-led defense of Europe.” The Pentagon and Hegseth didn’t respond to written requests for comment. But a senior Pentagon official told Reuters: “This is a serious review, designed to be rigorous, consultative and empirical.”
Mihail Kogalniceanu Air Base in Romania was built to make Americans feel at home. Its streets are named Alabama, Ohio, Alaska and George Washington. The base has hosted troops since 1999 and supported America's wars in Iraq and Afghanistan.
Last year, about half of the approximately 2,000 American troops in Romania, most of them living at the base, departed as the Trump administration began a radical realignment of the military presence in Europe. In Romania, a North Atlantic Treaty Organization country bordering Ukraine, the departures caused alarm: MK, as the base is known, sits on the alliance's eastern flank at a time when Russian drones have repeatedly crossed into NATO territory.
But when Reuters visited MK in July, the base told a more complicated story about President Donald Trump's effort to remake NATO. Nine KC-135 Stratotankers were parked there, deployed to refuel American jets and bombers during the Iran war. Their crews and support staff had partially offset the earlier troop departures, a reminder that Washington still relies heavily on European bases. More than two months later, the Stratotankers were still there.
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That paradox sits at the center of Trump's confrontation with the 32-nation alliance. He has threatened troop cuts, badgered allies over defense spending and denounced European governments for refusing to unconditionally support the -Israeli war against Iran. Yet a Reuters examination of military operations in Europe found that the Trump administration continues to invest in key NATO military facilities and is relying on them to project power across Europe, the Middle East and beyond.
To assess the effects of Trump's pressure campaign on NATO, Reuters interviewed more than 50 current and former Western officials, military officers, diplomats and defense experts, including senior Trump administration officials, congressional aides, and former ambassadors to NATO. Reuters journalists also visited bases used by NATO in Romania and Estonia, and observed NATO military exercises off the coast of North Carolina.
The reporting revealed an alliance under strain though not yet broken. Nine current and former officials told Reuters that congressional Republicans and Democrats, along with powerful defense contractors with big European customers, have the political clout to block a withdrawal from NATO – something Trump has repeatedly threatened to do.
Yet Trump's attacks are damaging the 77-year-old alliance in ways that European and American strategists alike say are difficult to reverse. Europe is increasingly questioning America's reliability as a security partner, Reuters found, and those doubts are now shaping defense spending, weapons procurement and long-term security planning across the continent.
Many of those interviewed described a slump in transatlantic trust that has weakened NATO's central deterrent: Article 5, the pledge that an armed attack on one member will be treated as an attack on all. A failing NATO led by an unreliable could be catastrophic for Europe's security as the region confronts an aggressive and openly expansionist Russia along its eastern borders.
And even as military spending surges across NATO, at least eight member countries – including Canada, Poland, Denmark and Spain – are beginning to diversify away from their reliance on weapons, technology and defense companies, Reuters found. This suggests Trump's campaign to force Europe to spend more on defense could ultimately backfire by prompting some allies to reduce their dependence on defense contractors and military technology.
"The pressure on Europe worked, but it created real uncertainty," said J.C. Lintzenich, a senior military intelligence official who left government in February after advising top Pentagon officials, the Director of National Intelligence and policymakers in Congress. "Europe is spending more, taking defense more seriously, and accepting greater responsibility – that is a real success. But there is also genuine concern in Europe that the United States could abandon them."
"President Trump has done more for NATO than anyone else," said White House spokesperson Olivia Wales. "He will always unapologetically advance America's interests." While Trump has taken credit for the rise in European defense spending, it has also been fueled by Russia's full-scale invasion of Ukraine in 2022, which has flattened cities, killed hundreds of thousands of people and sent millions fleeing across Europe.
"A strong alliance has allies that hold each other accountable," Matthew Whitaker, ambassador to NATO, told Reuters. In a statement, NATO pointed to recent remarks by Secretary General Mark Rutte, who praised Trump for helping drive higher defense spending across the alliance.
But Trump's ability to remake NATO has run up against significant constraints. Before leaving for a NATO ministerial meeting in Brussels in June, Defense Secretary Pete Hegseth had planned to announce a cut of roughly 25,000 troops in Europe, according to two officials. The proposed cuts – the scale of which has not been previously reported – would have pushed American force levels in Europe below a congressionally mandated 76,000-troop minimum signed into law last year.
Instead, Hegseth faced resistance within Trump's own administration and arrived at NATO's curved steel-and-glass headquarters in Brussels with a warning for allied defense ministers. The Pentagon would conduct a six-month review of America's force posture in Europe, with particular scrutiny of countries that say "no, or maybe, or wait and see" when Washington needs support. "This will be a real review," Hegseth said. "Some countries will fail."
The Pentagon has been tight-lipped about the review, but in August it prepared a document with 57 questions for allies aimed at measuring their military, financial and ideological commitment to the , according to a copy of the memo reviewed by Reuters. One question, for instance, asks whether a country has been "publicly supportive of foreign policy priorities."
The review exposed a struggle in Washington over how far the can reduce its role in Europe without undercutting its own military reach. Five senior congressional aides – both Republicans and Democrats – told Reuters there was growing bipartisan distrust of Hegseth's handling of NATO. One of the aides said Republican and Democratic senators were worried the Pentagon might announce "a move that might not be positive for NATO or even national security."
One possible outcome of the force review, said three people familiar with the matter, is that Hegseth could propose the same number that he wanted to announce in June: a 25,000 cut.
The White House has said the six-month review will "ensure irreversible momentum toward a European-led defense of Europe." The Pentagon and Hegseth didn't respond to written requests for comment. But a senior Pentagon official told Reuters: "This is a serious review, designed to be rigorous, consultative and empirical."
The has more than 81,000 military personnel in Europe, a number that fluctuates as troops rotate through the continent on deployments and exercises, according to government audits and congressional testimony reviewed by Reuters.
In the four years before Trump first took office in 2017, the averaged about 65,000 troops and other military personnel in Europe. That figure rose to 74,000 during his first term, then surged to 105,000 under former President Joe Biden after Russia's full-scale invasion of Ukraine in 2022. By the time Trump returned to office in 2025, the number had fallen back to roughly current levels.
The battle over NATO is part of Trump's broader upending of the international order the helped build after World War Two. His administration is challenging long-standing institutions, alliances and norms with a more transactional, "America First" approach that prizes dominance over treaties and multilateral cooperation. Previous Reuters reporting detailed Trump's assault on the global justice system through crippling sanctions against the International Criminal Court and his scrambling of American diplomacy by hollowing out embassies and threatening friends and foes alike.
Troops and trust
Most allies met Trump's demands for higher defense spending, turning NATO's potentially explosive Ankara summit in July into what Trump called "a very successful" meeting.
But the Pentagon's six-month review remains the central uncertainty hanging over the alliance. Some European officials believe NATO's military leadership can manage an eventual drawdown without exposing the continent's vulnerabilities. Others fear the process could trigger a competition for Washington's favor. In Romania and Poland, officials told Reuters they have lobbied discreetly but intensively to keep American troops on their territory.
"Why do all these countries want soldiers on their soil?" said George Scutaru, a Romanian defense expert and head of the New Strategy Center, a Bucharest think tank. "Because it's the best deterrent – a human shield."
The Iran war underscores how dependent Washington remains on European geography, even when relations with allies are strained.
Italy denied permission in late March for some military aircraft to land at the Sigonella air base in Sicily before heading to the Middle East, Reuters reported. But by late June, more than 500 military aircraft had transited Italian bases, including 343 through Sigonella and 211 through Aviano in the country's north, many of them carrying munitions, according to a third official.
Even so, Trump attacked Italian Prime Minister Giorgia Meloni in a June 20 post on social media, saying "she wouldn't even let us use Italy's landing strips or runways, a great logistical inconvenience." The Italian government didn't respond to a request for comment.
Since 1949, NATO has been a cornerstone of American power, helping the to station forces across Europe, deter adversaries, project military strength and anchor a bloc of democratic allies. In return, Europe gained the protection of the world's most powerful military, helping sustain an era of peace and prosperity unmatched in its modern history.
Europe is spending more, taking defense more seriously, and accepting greater responsibility – that is a real success. But there is also genuine concern in Europe that the United States could abandon them.
For generations, that bargain enjoyed broad support across party lines in Washington. But not from Trump. His position – that other countries freeload off protection – has stayed remarkably consistent across four decades of public life.
"A lot of people are tired of watching other countries ripping off the United States," he said in a 1987 interview on CNN. Allies had to pay up or "get out," Trump said during his 2016 presidential campaign. "And if it breaks up NATO, it breaks up NATO." In his first term, Trump demanded allies increase defense spending from 2% to 4% of gross domestic product. Just before returning to office in 2025, he pushed for 5%.
"If they don't pay, I'm not going to defend them," he told reporters in March 2025.
European allies and Canada spent 2.3% of their combined GDP on defense in 2025, according to NATO. All of them, apart from Spain, have agreed to spend 5% on defense and broader security-related investments by 2035.
Kay Bailey Hutchison, a former Republican senator who served as Trump's ambassador to NATO in his first term, said Trump seems to believe that the gains more through his relationships with the leaders of rival powers such as Russia and China than through alliances such as NATO. "I always wanted the president to understand that if our long-term adversary is China, we need allies," she said.
Despite those attacks on NATO, Trump has continued funding major infrastructure projects at European military facilities over his second term. In Spain, which Trump denounced at the Ankara summit as "a terrible partner in NATO" and "a wasted cause," Washington has shown no sign of pulling back from Naval Station Rota or Moron Air Base.
In May and June alone, the announced reinforcement of aircraft facilities and $400 million in construction contracts to Spanish companies at Moron to maintain and improve the base over the next decade.
Rota and Moron are difficult to replace. They offer access to the Atlantic and Mediterranean and extend military power into the Middle East and North Africa. At a press conference at the Ankara summit, Spanish Prime Minister Pedro Sanchez said the deployment of American forces in Europe was a "sovereign decision" of the and that Spain's military relations with it were "excellent."
In Romania, the has invested more than $100 million in the ongoing expansion of Mihail Kogalniceanu Air Base, alongside a roughly $2.7 billion project funded by Romania that aims by 2040 to make the installation the largest NATO air base in Europe, with capacity for up to 20,000 personnel.
Trump slammed then-Prime Minister Keir Starmer in March over Britain's limited support for strikes on Iran. But the is spending more than $4.2 billion on current and upcoming projects at seven air bases in Britain, according to a March presentation by a Air Force unit that manages base infrastructure. bombers have flown missions against Iranian targets from at least one of those British bases, reinforcing the strategic importance of Europe to military operations well beyond the continent.
But at least a dozen past and present officials from Europe, the and Canada cautioned that Trump doesn't need to formally withdraw from NATO to hobble the alliance. His anti-NATO rhetoric alone might signal to Russian leader Vladimir Putin that the West is divided and more vulnerable than it appears.
Those officials said they fear Putin is testing that assumption with a wave of sabotage incidents across the continent, which European countries blame on Russia. They include, in August alone, an attempted drone attack on a German airport and a fire at a Polish drone factory.
In July, just two days after Reuters visited Romania's MK Air Base, NATO scrambled Romanian fighter aircraft to intercept a Russian drone that had penetrated Romanian territory. It was shot down by a Romanian F-16 operating from another base. Two more drones, also believed to be Russian, were downed in the following days. Then, in late July, a Russian cruise missile landed in Poland, another front-line NATO ally.
Asked about the incidents in Germany, Poland and Romania, Russia's ambassador to Belgium, Denis Gonchar, denied any Russian involvement and called them "dirty provocations" by Ukraine and others who wanted to "drag NATO and the European Union into a direct conflict with Russia."
European officials, however, blame the increasingly brazen incursions on Moscow and say they are part of a campaign aimed at undermining support for Ukraine and testing NATO unity. Marius Lazurca, national security advisor to Romanian President Nicusor Dan, told Reuters that a drone shot down over Romania on August 16 was intercepted by a Spanish pilot flying a -made fighter jet, demonstrating NATO solidarity.
"It is clear that Russia is testing Romania's defense capabilities and NATO's response," said Scutaru, the Romanian defense expert.
Less clear to many allies is what Washington wants from them.
Poland and Germany have ramped up defense spending yet still face potential troop cuts. Denmark is spending a larger share of GDP on defense than the but remains the target of Trump's threats to seize Greenland. A spokesperson for Germany's Federal Foreign Office said the would continue to play a "vital role" as Europe takes more responsibility for its own defense. The Danish defense ministry didn't reply to a request for comment.
Adding to the uncertainty, Pentagon officials have explored punishing allies Trump viewed as disloyal. In an internal email previously reported by Reuters, Under Secretary of Defense for Policy Elbridge Colby discussed suspending Spain from NATO after Madrid refused to support strikes on Iran – even though the alliance has no mechanism to suspend a member. Allies arrived at the Ankara summit braced for confrontation, only to hear Trump swing from attacking Spain to praising the "tremendous love" he had felt at NATO.
Europe and canada look elsewhere
Across NATO, governments are not waiting for clarity from Washington. They are rearming at a pace unseen in decades and, in some cases, looking for alternatives to American military technology.
Trump's threats toward NATO, coupled with Russia's war against Ukraine, have fueled the surge in European defense spending. NATO said its European members and Canada boosted combined defense spending by 20% in 2025 compared with the previous year.
Trump predicted a windfall for defense contractors. "We will manufacture it, and they're going to be paying for it," he said at a White House meeting with NATO chief Mark Rutte in July 2025. "We're in for a lot of money." A year later, at the NATO summit in Ankara, Trump boasted that allies had increased defense spending by $150 billion in 2025, adding that "they all want American-made equipment."
But Reuters identified at least eight of NATO's 32 members – Canada, Poland, Denmark, Spain, Norway, Turkey, France and Germany – exploring ways to reduce their dependence on weapons, technology and defense companies as doubts grow about the durability of support.
Such doubts aren't surprising, said Wendy Gilmour, a former assistant secretary general for defense investment at NATO. Many people saw Trump's first election as a "fluke," she said, and assumed the would remain a reliable ally. "The second election feels more deliberate, and it feels like the is no longer the exceptional democracy that we all thought it was."
While Europe remains unable to replace some advanced military technology, countries including Canada and Poland are buying more non- equipment, from radar systems to jets, as they seek to reduce decades of reliance on defense firms.
That has sparked concern within the Pentagon. In a July social media post, Colby, the Pentagon's top policy adviser, argued that allies should collaborate with the defense industrial base "rather than trying in vain to replicate or supplant it."
Canada, which is embroiled in a trade war with Trump, offers a glimpse of the tensions emerging in the alliance. Three recently departed senior Canadian government officials told Reuters they have received mixed messages from the Pentagon about Canada's efforts to diversify defense procurement. In June, Canada chose a $1.7 billion Australian-made Arctic radar system over a competitor. A former senior Canadian official directly involved in the decision said the Pentagon supported the choice because the Australian firm promised to deliver the system years faster than its rival.
But Pentagon officials have expressed concern about Canada's recent decision to buy early-warning radar planes from Sweden, rather than the , and to consider purchasing some Swedish-made Gripen fighter jets rather than additional -made F-35s. Such actions made one Pentagon official question whether Canada was a "credible partner" in the mutual defense of North America, Reuters previously reported.
In a statement, Canada's defense ministry said it hasn't yet decided whether to buy more F-35s, beyond the first batch due to arrive this year, or to pursue an alternative. "The review of the F-35 is ongoing as work continues to ensure maximum economic benefits for Canadian businesses and workers," the ministry said.
Efforts to break dependence on weapons could have significant repercussions, said Gijs Tuinman, the Dutch minister of arms procurement and personnel until February. He said he believed anti-Trump sentiment in Europe could eventually push some governments to reconsider participation in major American defense programs, a shift experts say could cost companies billions.
"The risk is humongous. It's on the brink of happening actually," Tuinman said in an interview.
Lockheed Martin, which makes the F-35, told Reuters it is seeing "strong demand from NATO members" for its fighter jet and other products. Poland and Finland will receive their first F-35s this year, with Canada and Germany to follow, according to a Pentagon budget document.
Gonchar, Russia's Ambassador to Belgium, said the Russian threat was being exaggerated to encourage Europeans to keep buying expensive American military equipment.
Untangling Europe from decades of military integration cannot happen quickly. Manufacturing capacity takes years to build. Most new weapons take even longer to develop. Yet many European, American and Canadian officials told Reuters they increasingly view dependence on technology, supply chains and political leadership as a strategic risk for Europe.
"I don't think a responsible European leader can put the future security of their country entirely in the hands of the United States, which is of course what European countries have done since the end of the Cold War," said Chris Chivvis, the senior intelligence officer for Europe during Trump's first term. "So there's a real sea change in Europe."
European Commission President Ursula von der Leyen captured the new mood in her annual State of the European Union address on Wednesday.
In a 70-minute speech that didn't once mention the , the EU chief warned of a "fracture in the international rules-based system" and said Europe "must urgently reimagine our partnerships." Then she invited Canada to become the EU's first "associate member," signaling closer cooperation on defense, trade and other issues. Afterward, Canadian Prime Minister Mark Carney, who attended the speech at the European Parliament in Strasbourg, received a standing ovation.
Europe revolts
At least publicly, European governments continue to project confidence in the alliance. Four governments that responded to Reuters' requests for comment – Portugal, Norway, Germany and Spain – said NATO remained united despite recent strains. Norway described the as "our most important ally," while Portugal said NATO was inconceivable without it.
The spokesperson for Germany's Federal Foreign Office said contractors still account for a "significant share" of German military procurement.
But for NATO's deterrent to be effective, many European officials privately say Russia and other adversaries must believe that the would protect Europe. Multiple recent opinion surveys have shown that many Europeans doubt the would come to the continent's defense, and that record numbers dislike Trump and distrust his country.
A July Pew Research Center survey found that China is now viewed more favorably than the in most of the 36 countries surveyed, including nine NATO members: Canada, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden and Turkey.
"That's really troubling," Senator Jeanne Shaheen, the senior Democrat on the Senate Foreign Relations Committee and co-chair of the Senate NATO Observer Group, said in an interview. "They are no longer viewing President Trump as a reliable ally."
No issue has damaged trust more than Trump's designs on Greenland, according to a dozen current and former Western government and military officials.
"This is not the United States we knew," said Jody Thomas, Canada's chief national security advisor from 2022 to 2024. "What they're doing is no longer reasonable, it's no longer rational."
In a speech at Davos in January, Trump ruled out taking control of the Danish territory by force. But he still covets it. A photo montage posted on his social media account in August showed him looming large over its mountains and houses, along with the words, "Hello, Greenland!"
Is NATO ready to fight? The Ukraine war is raising doubts among military analysts
KYIV, Ukraine – Russia's full-scale invasion of Ukraine has killed hundreds of thousands of people. It has also served as a proving ground for new weapons systems and raised an uncomfortable question for the North Atlantic Treaty Organization: Is the alliance prepared for the next war it might have to fight?
Five Ukrainian and Western defense officials told Reuters that developments on the battlefield are moving so quickly that some NATO weapons and tactics risk becoming outdated. While Ukraine – which is not an alliance member – adapts in weeks, NATO buys and develops systems over years, sometimes decades.
The Ukraine war and President Donald Trump's haranguing of European allies have prompted many NATO members to dramatically increase their defense spending. The Pentagon is currently reviewing its military presence in European countries, which Trump has accused of sponging off protection and refusing to help prosecute his unpopular war against Iran.
Denys Shtilerman, the co-owner and chief designer of Fire Point, a leading Ukrainian missile and drone builder, told Reuters that tanks are now "worthless" because a drone costing about $5,000 can destroy one. Yet Europe still spends heavily on tanks – which, say many military analysts, still have a key role to play in future battles.
Cheap drones have also transformed warfare in other ways. Troops gathering in groups or large vehicle convoys all become far easier targets.
"They are good at storming positions," Oleksandr Pivnenko, Commander of the National Guard of Ukraine, said of the international troops his units trained with last year. "But if there's a drone overhead and you don't even look up, what do you think will happen to your squad?"
In June, Reuters attended a NATO military exercise near Paldiski in Estonia – a small Baltic country now fortifying its 210-mile border with Russia – in which American and European troops treated dozens of simulated casualties at wartime field hospitals. But the exercise took place with the assumption that NATO would command the airspace above the hospitals – no longer a given in the age of cheap, stealthy, long-distance drones.
Rather than simply receiving NATO training and assistance, Ukrainian officials described a growing role for Ukraine in teaching the alliance lessons drawn from the war with Russia. Yet they also said NATO's military bureaucracy struggles to absorb those lessons. A Ukrainian officer who underwent NATO psychological operations training in Romania told Reuters that some alliance training materials still relied on case studies from World War Two. NATO didn't respond to questions about the officials' criticism of its training and bureaucracy.
The Ukraine war has also exposed a vulnerability that NATO officials say is far harder to solve: air and missile defense. Russia's relentless barrages against Ukrainian cities have highlighted Europe's dependence on sophisticated anti-missile systems such as the Patriot, first used in the 1991 Gulf War. Ukraine has a critical shortage of Patriot interceptors – the missiles fired to destroy incoming threats.
Fearing that its reliance on Patriots might become a strategic vulnerability, Europe is building non- alternatives. Ukraine is awaiting delivery of the new French-Italian SAMP/T-NG air-defense system, designed to intercept ballistic missiles. France has promised to accelerate its deployment to Ukraine, and European diplomats previously told Reuters it was expected to arrive by next spring.
In a statement, the Ukrainian defense ministry said its soldiers and NATO's had much to learn from each other, hailing Ukraine's use of drones and radioelectronic warfare as "globally unmatched" and praising European efforts to help tackle Russia's drone and missile bombardments.
In July, Ukraine and nine European allies launched an air-defense coalition that includes plans to jointly develop a new anti-ballistic missile system. Known as Freyja, the project is a consortium of about a dozen companies with Fire Point as the lead private-sector partner. The goal is to build a system that is cheaper and faster to produce than the Patriot, while ensuring that Europe, not the , controls its manufacture.
"If you spend $20 billion on your air defense system, you must be independent in your security," said Fire Point's Shtilerman.
Andrew R.C. Marshall reported from Constanta and Paldiski; John Shiffman and Humeyra Pamuk from Washington; Phil Stewart from Washington and the North Carolina coast; Luiza Ilie from Constanta; and Victoria Waldersee from Madrid. Additional reporting by Andrew Gray in Brussels and Idrees Ali in Washington. Design by John Emerson. Video production by Diane To and Vanesse Chan. Edited by Jason Szep.
