Trump Threatens NATO Withdrawal Amid Iran Crisis: What U.S. Law Says

President Donald Trump escalated tensions with Western allies on Wednesday, threatening to pull the United States out of NATO after European members refused to deploy naval forces to unblock the Strait of Hormuz near Iran. The dramatic threat intensifies an ongoing rift between Washington and its longtime allies as the Iran conflict — sparked by U.S. and Israeli airstrikes on February 28 — continues to reshape global security dynamics.

Trump told Reuters he was "absolutely" considering leaving the 77-year-old military alliance, citing deep frustration with European partners. His remarks followed Defense Secretary Pete Hegseth's refusal to reaffirm America's commitment to NATO's collective defense clause, a move experts called more significant than any legal threat.

Whether Trump can legally exit NATO remains a contested question. The U.S. Constitution grants the president authority to make treaties with Senate approval but says nothing about withdrawing from them. Under NATO's founding 1949 North Atlantic Treaty, any member nation may exit after providing one year's notice — though no country has ever done so.

In 2023, Congress passed legislation requiring a two-thirds Senate majority before any president could withdraw the U.S. from NATO. Signed by President Biden, the law also prohibits federal funds from being used to facilitate a withdrawal. However, a 2020 Justice Department opinion argued that treaty withdrawal falls under presidential — not congressional — authority, and a 2026 Congressional Research Service report noted that the 2023 law could face constitutional challenges in court.

Legal experts warn that even if Trump moves forward, court challenges would face significant hurdles, including questions of legal standing. With the Supreme Court's conservative majority frequently siding with the executive branch, a unilateral NATO exit may be difficult to stop through legal channels alone.