Europe’s Security at a Crossroads: Rethinking NATO Without the U.S. Europe is facing a new geopolitical reality: the United States’ role as the backbone of NATO—the alliance that has underpinned the continent’s security for nearly 80 years—is no longer guaranteed. Former President Donald Trump’s hostility toward Ukrainian President Volodymyr Zelensky, his overtures to Russian President Vladimir Putin, and his recent statements questioning whether the U.S. would defend NATO allies “if they don’t pay” have forced European leaders to confront a once-unthinkable question: Can they still rely on Washington for security at a time when Europe is experiencing its most significant conflict since World War II? However, NATO without the U.S. is far from powerless. 

 The alliance’s 31 other member states collectively field over a million troops and possess advanced weaponry, along with the financial resources and technological expertise necessary to defend Europe, according to military analysts. The U.S. and Germany are NATO’s top financial contributors, each covering nearly 16% of the alliance’s military budget, civil budget, and security investment program, followed by the U.K. at 11% and France at 10%, according to NATO figures. Analysts suggest that Europe could compensate for the loss of U.S. support if its nations coordinate their defense spending effectively. If European countries invest in the right military capabilities, they could form a credible conventional and even nuclear deterrent against Russia, said Ben Schreer, Europe executive director of the International Institute for Strategic Studies (IISS), in a February call with CNN and other journalists. “Europe alone still has the capacity to muster the resources it would need to defend itself,” Schreer noted. “The question is whether it is willing to do so.”  A Transatlantic Rift That May Be Irreparable For more than 75 years and under 14 different U.S. presidents—including Trump’s first term—the U.S. has been NATO’s central pillar. 

 During the Cold War, American troops in Europe deterred Soviet expansion, a commitment that continued through NATO’s interventions in the Balkans in the 1990s and Washington’s leadership in supporting Ukraine until the start of Trump’s second administration in January 2025. Now, analysts suggest that the historic transatlantic partnership may be fracturing. Trump’s Oval Office confrontation with Zelensky—after which he suspended U.S. aid to Kyiv—felt like a deeper break, not only with Ukraine but with Washington’s long-standing strategy of leading the “free world,” said Dan Fried, a senior fellow at the Atlantic Council and former U.S. assistant secretary of state for Europe. John Lough, a former NATO official and now an associate fellow at Chatham House, sees an even more profound shift. “The United States increasingly views Europe more as a competitor than an ally,” Lough told CNN, adding that Washington’s commitment to NATO’s collective defense is now uncertain. This shift, he argues, is irreversible. “Once you start to lose part of that commitment, you effectively lose it all,” Lough said. Some European officials are even beginning to question whether Washington should now be seen as an adversary rather than an ally, he added. 

A Stronger Europe Without the U.S.? Not all analysts view a NATO without U.S. involvement as a weakness. “As soon as U.S. allies become convinced that they can no longer rely on Washington for their defense, they will be compelled to strengthen their own capabilities,” wrote Moritz Graefrath, a security and foreign policy expert at William & Mary’s Global Research Institute, in War on the Rocks. “Paradoxically, the withdrawal of U.S. forces could result in a stronger, not weaker, Europe,” he argued. Polish Prime Minister Donald Tusk believes this transformation has already begun. “Europe as a whole is fully capable of winning any military, financial, or economic confrontation with Russia—we are simply stronger,” Tusk said ahead of a European Union summit. “We just needed to start believing it, and today it seems to be happening.”  What Does Europe Have? In principle, a European-led NATO could be a formidable force. Turkey has NATO’s largest military outside the U.S., with 355,200 active personnel, according to The Military Balance 2025, published by IISS. France (202,200), Germany (179,850), Poland (164,100), Italy (161,850), the U.K. (141,100), Greece (132,000), and Spain (122,200) also maintain substantial forces. For ground troops—the core of any defensive force—Turkey again leads with 260,200 personnel, followed by France (113,800), Italy (94,000), Greece (93,000), Poland (90,600), the U.K. (78,800), Spain (70,200), and Germany (60,650), according to IISS data. By comparison, the U.S. had approximately 80,000 troops stationed in NATO countries as of June 2024, most of them in Germany (35,000), Italy (12,000), and the U.K. (10,000), according to the Congressional Research Service. 

 In terms of advanced weaponry, major European NATO members possess military assets that surpass those of Russia in key areas. For example, while Russia operates only one aging aircraft carrier, the U.K. has two state-of-the-art carriers capable of launching F-35B stealth fighters. France, Italy, and Spain also field aircraft carriers or amphibious ships that can deploy fighter jets. Beyond conventional forces, France and the U.K. maintain independent nuclear arsenals, each with nuclear-powered ballistic missile submarines. NATO’s European members collectively operate around 2,000 fighter and ground-attack aircraft, including a growing number of next-generation F-35s. On the ground, European NATO countries field advanced tanks like Germany’s Leopard and the U.K.’s Challenger, both of which have seen action in Ukraine. Additionally, they possess sophisticated long-range missiles such as the Franco-British SCALP/Storm Shadow, which has proven effective against Russian targets.Preparing for a Post-U.S. NATO Europe is already taking steps to bolster its military capabilities independently of the U.S. *The Military Balance 2025* notes that in 2024, six European nations launched a joint effort to develop ground-launched cruise missiles, expanded munitions production, and diversified their defense supply chains by turning to countries like Brazil, Israel, and South Korea. Even if the U.S. were to fully withdraw from Europe, it would leave behind critical military infrastructure. Washington maintains 31 permanent bases across Europe—spanning air, naval, and ground forces—facilities that would remain available to host nations in the event of a U.S. pullout. Graefrath also argues that a U.S. withdrawal would not permanently sever military ties. “The infrastructure would remain largely intact, allowing the U.S. to reengage militarily in Europe should the need arise,” he wrote. 
 
A Defining Moment for Europe With America’s role in NATO increasingly uncertain, Europe stands at a crossroads. While the continent has long relied on Washington’s military leadership, the shifting geopolitical landscape is pushing European nations toward greater self-reliance. Whether this moment leads to a stronger Europe—or a more vulnerable one—depends on the choices its leaders make in the coming years.