Rising tensions over Iran have exposed deepening divisions within North Atlantic Treaty Organisation (NATO), prompting fresh debate over whether the alliance could survive without the United States.

Analysts say disagreements between US President Donald Trump and European allies are not new, but the latest crisis has intensified them significantly.

Trump has reacted sharply to what he sees as insufficient European support for Washington’s stance on Iran, calling it a lasting stain on the alliance.

German Chancellor Friedrich Merz described the situation as a “transatlantic stress test,” acknowledging that NATO’s core strength is being challenged.

Experts note that a formal US withdrawal would require a two-thirds majority in the Senate or approval from Congress, making an immediate exit unlikely. However, Washington could still weaken NATO through other measures.

These include withdrawing around 84,000 US troops from Europe, closing military bases, and reducing defence cooperation — steps that could significantly undermine the alliance’s foundation.

Although European nations have increased defence spending by over 60% between 2020 and 2025, they remain heavily reliant on the US for intelligence, missile defence, logistics, and satellite capabilities.

Reports suggest Europe would need more than $1 trillion and at least a decade to build a comparable military capacity.

Some analysts believe NATO could still endure in a different form, given strong incentives for continued European defence cooperation.

Meanwhile, concerns persist over Russia, which German military officials say could regain strength between 2027 and 2029, posing a renewed threat.

Experts stress that NATO has historically served US interests as well, pointing to the alliance’s collective response after the September 11 attacks, when European allies joined operations in Afghanistan.

They conclude that while NATO’s future remains uncertain, any US disengagement would carry significant strategic consequences for both sides of the Atlantic.