At the Edge of the Alliance: How Trump's NATO Skepticism Fundamentally Reshapes Europe's Defense Architecture

The transatlantic security order, which has formed the foundation of Western defense policy since 1949, is undergoing its most severe stress test since the end of the Cold War during these April days of 2026. What could be dismissed just a few months ago as a rhetorical pressure tactic by the Trump administration has developed into a tangible existential crisis, forcing European capitals to fundamentally rethink their positions. The developments of the past three weeks — from Trump’s public consideration of a NATO exit to the rejection of European support in the Iran conflict, and new French nuclear doctrines — paint a picture of an alliance in upheaval, the outcome of which is completely uncertain.

On April 1, 2026, U.S. President Donald Trump publicly stated that he was considering a withdrawal of the United States from NATO. The justification was that European allies had refused to support the United States in the war against Iran. On Truth Social, Trump wrote after a meeting with NATO Secretary General Mark Rutte that NATO had not been there when it was needed. Rutte had previously attempted to placate the U.S. President — the effort failed miserably. The message from the White House was unmistakable: The alliance commitment is no longer considered mutual by Washington.

This vacuum of trust has sparked a debate in Europe that would have been unthinkable just two years ago. A survey by European Pulse, conducted from March 13 to 21 by Cluster17 for POLITICO and beBartlet among 6,698 respondents in six EU countries, found that only 35 percent of Europeans now view the United States as a close ally or partner. Sixty percent classify the U.S. as a competitor or threat. At the same time, 86 percent support the establishment of independent European defense capabilities, and 69 percent advocate for the creation of a common European armed force. These figures represent a historic turning point in European security perception.

EU Defense Commissioner Andrius Kubilius used the survey results to bolster his call for a European army. In a POLITICO interview on April 10, Kubilius emphasized that Europeans increasingly understand that mere coordination of 27 national armies is insufficient. People want Europe to become much stronger in defense, and secondly, they want to see a real military force, said the Lithuanian commissioner. On the same day, Kubilius flew to the Pentagon to negotiate the expansion of European defense capabilities — a paradoxical situation that highlights the tensions within the alliance.

While the debate over a European army is being conducted at the institutional level, France has already taken concrete steps that fundamentally change the nuclear dimension of European security. President Emmanuel Macron announced on March 2 at the naval base Île Longue in Brittany the most significant change to French nuclear doctrine since the end of the Cold War. Against the backdrop of the submarine Téméraire, Macron announced an increase in the French nuclear arsenal, which currently comprises about 290 warheads. An increase is essential to maintain the credibility of deterrence, the president stated. A single submarine like the one behind him carries a striking power equivalent to the sum of all bombs dropped over Europe during World War II.

Even more remarkable than the quantitative buildup is the qualitative reorientation. For the first time, Macron explicitly named Germany, Poland, the Netherlands, Belgium, Greece, Sweden, and Denmark as partners for deepened nuclear cooperation. This cooperation is intended to include joint nuclear exercises and possibly the temporary stationing of French nuclear-capable fighter jets in allied countries. While Macron emphasized that France does not aim to replace the American nuclear role in Europe, the strategic message was clear: Paris is positioning itself as the nuclear anchor of an increasingly autonomously acting European defense.

Norway has already signaled its readiness to engage in nuclear talks with France, as POLITICO reported on March 3. Finland, in turn, decided on March 5 to allow the import of nuclear weapons on Finnish territory — further evidence of how the Nordic and Baltic NATO members are responding to the reliability question of the American security guarantee. Both decisions would have been unthinkable without the loss of trust in the American security guarantee.

At the conventional level, the crisis has also accelerated concrete measures. On February 20, Germany, France, Italy, Poland, and the United Kingdom agreed on a joint initiative to produce cost-effective drones within a year. The project aims to close the operational gaps that have become apparent due to the Ukraine war and the increasing estrangement from the U.S. At the same time, the transatlantic economic conflict in the defense sector is intensifying: The Pentagon is aggressively lobbying against the European Buy-European initiative and has warned Brussels not to push American defense companies out of the market.

NATO itself published its annual report on March 26, which contained at least one positive piece of news: All 32 member states reached the two percent target for defense spending as a percentage of GDP for the first time in 2025. However, the discrepancies remain significant. While Poland leads with over four percent of GDP, countries like the Czech Republic fall below the new five percent target that Washington is now demanding. U.S. diplomats have already publicly reprimanded Prague — a taste of the pressure the Trump administration will exert on allies.

However, perhaps the most important strategic question remains unresolved: What happens if Washington actually carries out its NATO exit? Article 13 of the North Atlantic Treaty allows any member to withdraw after a one-year notice period. Legally, this would be possible, although politically it would have unpredictable consequences for the global security architecture. The European reactions — Macron's nuclear realignment, Kubilius's call for an EU army, the drone initiative of the five major European powers — suggest that Europe's leaders are seriously preparing for this scenario.

Mark Rutte, who must navigate between the fronts as NATO Secretary General, has so far tried to hold the alliance together through personal diplomacy. However, his meeting with Trump on April 1 showed the limits of this approach. The Iran crisis has exposed the structural cracks in the alliance: While Washington demands European support for its military campaign in the Middle East, most European capitals reject participation. Spain, under Prime Minister Pedro Sánchez, went so far as to explicitly prohibit the U.S. from using Spanish military bases for attacks on Iran.

The coming weeks will show whether NATO can withstand this stress test or whether Europe will be forced to establish an entirely new security architecture. The course has been set — the only question is whether it can still be changed.