Former Rep. Liz Cheney (R-Wyo.) on Monday blasted former President Trump's suggestion that he encouraged Russia to attack "delinquent" NATO allies, saying "no sane American President would encourage" such an action.

Why it matters: The comments set off a fresh round of worry among some anti-Trump Republicans and international observers on how a second Trump presidency could impact the United States' role in the international military alliance.

Driving the news: Trump recounted Saturday that during his presidency, he had told the leader of an unidentified NATO member he would "encourage" Russia "to do whatever the hell they want" if the NATO member were behind on its membership payments.

• "You didn't pay. You're delinquent?" Trump told the audience at a campaign rally in South Carolina Saturday. "No, I would not protect you."
• The crowd responded with cheers.

What they're saying: Cheney, a Trump critic who lost her seat in Congress to an opponent he endorsed, on X Monday said: "No sane American President would encourage Putin to attack our NATO allies." She noted that NATO is critical for U.S. national security.

• "No honorable American leaders would excuse or endorse this," she wrote.

Current and former GOP presidential candidates also weighed in.

• Former New Jersey Gov. Chris Christie, who suspended his presidential campaign earlier this year, told NBC's "Meet the Press" Sunday that Trump's comments were "consistent with his love for dictators."
• Nikki Haley, who has lost every GOP primary this year to Trump, told CBS' "Face the Nation" Sunday that while it is important for NATO allies to "pull their weight ... there are ways you can do that without sitting there and telling Russia, have your way with these countries."

Meanwhile, other Republicans sought to defend Trump's comments.

• Sen. Marco Rubio (R-Fla.) downplayed Trump's comments Sunday on CNN, saying that "virtually every American president at some point, in some way, has complained about other countries in NATO not doing enough."
• "Trump's just the first one to express it in these terms," he added.
• Sen. Lindsey Graham (R-S.C.) told the New York Times Sunday that "all I can say is while Trump was president nobody invaded anybody. I think the point here is to, in his way, to get people to pay."

Context: During his presidency, Trump regularly bucked tradition by criticizing global alliances and agreements long supported by the U.S.

• Trump repeatedly called on NATO allies to increase defense spending and even reportedly discussed withdrawing the U.S. from the alliance.
• As president, Trump criticized the trade practices of G7 allies and hit out at organizations like the World Trade Organization, the UN Human Rights Council and OPEC.
• Trump also pulled the U.S. out of the landmark Paris Climate Agreement and temporarily halted funding for the World Health Organization at the start of the COVID-19 pandemic.

The bottom line: For his part, NATO Secretary-General Jens Stoltenberg responded to Trump's comments by emphasizing the crucial nature of NATO's unity.

• "Any suggestion that allies will not defend each other undermines all of our security, including that of the U.S., and puts American and European soldiers at increased risk," he said in a statement Sunday, the Wall Street Journal reported.