US President Donald Trump’s disdain for NATO allies dates back to before he first took office. U.S. leaders have long kept the alliance under stress, from anger over relatively low defense spending to recent threats to take over Greenland, a territory from fellow NATO member Denmark.
But analysts say President Trump’s decision by NATO allies not to join the war against Iran has deepened the rift to an invisible level. President Trump this week said the lack of support from both countries was a “stain that will never go away” on the alliance. German Chancellor Friedrich Merz was even more blunt hours later, saying the conflict had “become a transatlantic stress test.”
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These exchanges highlight a central question exposed by the Middle East crisis, and experts say NATO can no longer afford to delay. That is, can the transatlantic alliance survive, especially if the United States withdraws?
“Neither this administration nor the next administration will bring NATO back to business as usual,” said Jim Townsend, a nonresident senior fellow at the Center for a New American Security. “We’re closer to breaking than ever before.”
Mr. Trump cannot withdraw the United States from the alliance on a whim.
To formally do so, he would need a two-thirds majority in the U.S. Senate or approval by an act of Congress, but NATO still enjoys broad support among many members of both major U.S. political parties, making this scenario unlikely to materialize anytime soon.
But there are other things President Trump can do. If an ally is attacked, the United States has no obligation to come to its aid. Article 5 of the treaty provides for collective self-defense obligations for member states, but does not automatically force a military response, and there is skepticism among allies about whether the United States will come to their aid.
The US could also move some 84,000 US troops deployed across Europe out of the continent. The Wall Street Journal reported Wednesday that President Trump is considering moving some U.S. military bases out of countries deemed useless during the Iran war and relocating them to more supportive countries. It could close U.S. military bases and suspend military cooperation with allies.
Such a withdrawal would be damaging enough, as America’s security for Europe has supported NATO since its creation.
“He doesn’t need to leave NATO to weaken it. By saying he might leave, he has already undermined its credibility as an effective alliance,” said Stefano Stefanini, Italy’s ambassador to NATO from 2007 to 2010 and a senior adviser to the Italian president.
Still, allies are not powerless. Russia’s invasion of Ukraine revealed the weakness of Europe’s defense industry and its deep dependence on the United States. This, coupled with a number of diplomatic crises in the US-NATO partnership, including President Trump’s threat to take control of Greenland, has prompted European allies to invest more in defense forces. Between 2020 and 2025, member states’ defense spending increased by more than 62%.
However, according to a report by the International Institute for Security Studies (IISS), areas where Europe suffers from over-reliance on the United States include the ability to strike deep into enemy territory, intelligence, surveillance and reconnaissance, space-based capabilities such as satellite intelligence, logistics, and integrated air and missile defense.
These challenges remain significant. Filling them will take more than a decade and will cost about $1 trillion to replace key elements of U.S. conventional military capabilities. Europe’s defense industry is struggling to scale up production quickly, and many European militaries are falling short of their troop recruitment and retention goals, according to an IISS report.
Still, some experts believe that creating a European NATO is possible. Minna Alander, an analyst at the Stockholm Center for Eastern European Studies at the Swedish Institute for International Affairs, said NATO has been a structure for military cooperation between European countries for many years.
“Therefore, NATO can survive an Iran war or even a U.S. withdrawal, because European countries have an incentive to preserve NATO, even if in a fundamentally different form,” Allander said.
For some, that deadline is 2029. Germany’s Chief of Defense Staff General Carsten Breuer estimates that by that point Russia may have regrouped enough forces to attack NATO territory. “But they could start testing us sooner,” Breuer said last May, ordering the German army to be fully equipped with weapons and other supplies by then. Some estimate that Moscow could pose that threat as early as 2027.
So what about the United States, could it do better without NATO?
Stefanelli, the former ambassador, said discussions about NATO are often “warped” to portray the alliance as solely about protecting Europe from Russia and as a favor to the continent.
NATO is an alliance network that was born at the beginning of the Cold War against the Soviet Union. For decades, the United States has fought to draw as many countries into its alliances as possible, treating countries that refuse to join them as friends of enemies.
After the September 11, 2001 attacks on the United States, NATO invoked Article 5 for the first and only time to support Washington and send troops to fight in Afghanistan. Thousands of military personnel died there, including nearly 500 from Britain and dozens from France, Denmark, Italy, and other countries.
And during the Iran war, European bases became useful bases for the U.S. military, even as many countries publicly distanced themselves from the conflict.
“NATO serves American interests, and President Trump has no problem ignoring these aspects,” said Farinelli, a former ambassador. “Europe has its share of responsibility for not investing in defense and creating strong dependence, but it is simply wrong to think that NATO only serves Europe’s strategic interests.”
