This item is part of Watching Washington, a regular dispatch from CBC News correspondents reporting on U.S. politics and developments that affect Canadians.
Trump-proof NATO? The United States Congress is on it. American lawmakers have moved to prevent any U.S. president from unilaterally withdrawing from the international alliance.
The potentially historic move came in an annual defence-spending bill that just passed the Congress on Thursday, in a largely bipartisan final vote of 310-118.
One tiny section of the massive $886 billion US National Defense Authorization Act includes a string of rules for a NATO withdrawal.
It says no president shall suspend, terminate, denounce or withdraw from NATO without either an act of Congress or the approval of two-thirds of the U.S. Senate.
It also says a president must notify Congress 180 days before undertaking a withdrawal plan, among other conditions spelled out in the bill.
The legislation had already passed the Senate; it was approved Thursday in a final vote in the House of Representatives and is now expected to become law with President Joe Biden's signature.
The context is Donald Trump. Even if he's not mentioned in the bill text, he's the inspiration for it. The former U.S. president increasingly appears like the front-runner in next year's election, with the strongest polls of his career.
And he's notoriously critical of NATO.
Aides say Trump discussed withdrawing in his first term. One ex-aide, John Bolton, has opined that Trump would withdraw from the alliance in a second term.
Trump's current platform says, if re-elected, he would conduct a review of NATO's mandate. It's laid out in language not normally used by a U.S. president.
"We have to finish the process we began under my administration of fundamentally re-evaluating NATO's purpose and NATO's mission," says Trump's election plan.
"Our foreign policy establishment keeps trying to pull the world into conflict with a nuclear-armed Russia based on the lie that Russia represents our greatest threat. But the greatest threat to Western civilization today is not Russia. It's probably, more than anything else, ourselves and some of the horrible, U.S.A. hating people that represent us."
The U.S. election is less than a year away. We'll know then whether Trump is returning to office, and after that what his plans are for NATO.
Until then, this new provision remains hypothetical. There's no way of knowing if it would withstand a constitutional challenge in court, on the grounds that it usurps a president's role in foreign affairs.
Sen. Tim Kaine, a Virginia Democrat, was a co-sponsor of the NATO measure and saluted the decision to adopt it. (Leah Millis/Reuters)
It's also an open question how effective the bill would be. For example, it's unclear how it would commit an anti-NATO U.S. president to act militarily in a case where NATO invoked its Article 5 mutual defence clause.
But for now, the law might give some reassurance to jittery U.S. allies, worried about a U.S. withdrawal, which would be virtually fatal to the alliance.
The senators who sponsored the NATO measure saluted its adoption Thursday in Congress.
Marco Rubio, a Republican from Florida, thanked his colleagues for adopting the bipartisan measure.
"No U.S. president should be able to withdraw from NATO without Senate approval," Rubio posted on X, formerly known as Twitter.
The other co-sponsor, Democrat Tim Kaine of Virginia, said: "America is stronger amongst our allies — this strong bipartisan vote is a testament to that."