Trump says he might withdraw the U.S. from NATO, even though the law says he can't without Congress' approval

Washington — President Trump says he's considering withdrawing the U.S. from NATO, after years of complaining the alliance's member countries aren't paying enough for their own defense. And since he began the war with Iran, the president has been lashing out about the lack of support from NATO allies. 

A law passed by Congress in 2023 — and spearheaded in part by Marco Rubio, now the secretary of state — bars the president from doing so without approval from the legislative branch. The existence of that law may not stop Mr. Trump from trying to pull the U.S. out of the 77-year-old alliance.

Here's what to know about the U.S.' membership in NATO:

What is NATO?

The North Atlantic Treaty Organization is a defensive alliance designed to keep the U.S., Canada and Europe safe in the wake of World War II. 

Formed in 1949, the alliance initially included 12 countries, but has swelled to 32 members. The latest countries to join NATO include Finland in 2023 and Sweden in 2024.

NATO's aim is to "guarantee the freedom and security of its members through political and military means." At its core is Article 5, which states that an attack on one NATO ally will be considered an attack on all. 

Why has Trump suggested leaving NATO?  

For years, Mr. Trump has taken issue with defense spending and contributions by NATO's member countries, and he's often referred to allies as unreliable partners, criticizing the alliance as a one-way street.

While running for his second term in 2024, Mr. Trump put intense pressure on NATO members to increase their defense spending. At the time, he pledged not to withdraw the U.S. from the alliance if other countries paid their fair share. Ultimately, the pressure led member countries to agree to a dramatic increase in their defense spending.

But the war with Iran has exacerbated tensions once more, as NATO allies have been reluctant to assist the U.S., with many denying the U.S. permission to use their air space or airfields in recent days. And the president's frustration with the alliance has appeared to increase as member countries have resisted his calls to send ships to reopen the Strait of Hormuz. 

Asked by Britain's Telegraph newspaper Wednesday whether he'd reconsider U.S. membership in NATO after the Iran war, Mr. Trump said it's "beyond reconsideration," while calling the defense alliance that the U.S. helped forge a "paper tiger." The president also told Reuters that he is "absolutely" considering an attempt to exit the alliance. But whether those comments are part of an effort by the president to exert leverage over NATO allies remains to be seen.

Secretary of State Marco Rubio shared the president's sentiment, telling Fox News on Tuesday that "unfortunately, we are going to have to reexamine whether or not this alliance, that has served this country well for a while, is still serving that purpose, or is it now become a one-way street."

Rubio acknowledged that as a senator, he was a staunch supporter of NATO. But he argued that if the U.S. is unable to use military bases in Europe during its war with Iran, then U.S. membership is going to have to be reconsidered. 

"After this conflict is concluded, we are going to have to reexamine that relationship," Rubio said. "We're going to have to reexamine the value of NATO and that alliance for our country. Ultimately, that's a decision for the president to make, and he'll have to make it."

The president has indicated in recent weeks he believes he can pull the U.S. out of NATO on his own, telling reporters last month that "I don't need Congress for that decision," and "I can make that decision myself."

Can the president pull the U.S. out of NATO?

NATO's Article 13 states that any member country may withdraw one year after providing a "notice of denunciation" to the U.S. government. But Congress approved legislation in 2023 aimed at preventing a president from unilaterally moving to leave NATO. At the time, lawmakers expressed concern that Mr. Trump could attempt to withdraw the U.S. from the alliance if he returned to office. 

Democratic Sen. Tim Kaine of Virginia and Rubio were the lead sponsors of the provision, which was included in the National Defense Authorization Act for fiscal year 2024 and signed by President Joe Biden.

The law states that the president "shall not suspend, terminate, denounce, or withdraw the United States from the North Atlantic Treaty, done at Washington, DC, April 4, 1949, except by and with the advice and consent of the Senate, provided that two-thirds of the Senators present concur, or pursuant to an Act of Congress."

Senate Minority Leader Chuck Schumer said in a post on X on Wednesday that the Senate "will not vote to leave NATO and abandon our allies just because Trump is upset they wouldn't go along with his reckless war of choice." The Senate Democratic caucus is made up of 47 members, who would all but certainly oppose the move, along with many Senate Republicans. 

But some experts argue that the president could cite executive authority to sidestep the law, in a move that would almost certainly prompt legal challenges. 

Meanwhile, even without an official exit, others say the president's increasingly hostile stance toward the alliance may leave it weakened. Already, the U.S. has taken on a smaller role in military exercises as the administration has put pressure on European nations to step up their defense spending. And some have pointed to concerns that the U.S. may not honor its Article 5 obligations or continue to extend its nuclear deterrence to member countries.

Ian Bremmer, president and founder of the Eurasia Group, noted in a post on X that the president can't legally withdraw from NATO without the Senate's consent. But if NATO members "can't trust" that the U.S. will honor Article 5, he said, "the alliance is already broken in the way that matters most."