"My reaction is, NATO is not in jeopardy," Rubio said in an interview broadcast Wednesday on Fox News when asked about Merz's comments.

"The only thing that puts NATO in jeopardy is the fact that we have NATO allies who barely have militaries, or whose militaries are not very capable, because they've spent 40 years not spending any money on it," Rubio said.

"We're not saying do your own thing. We're saying do more. It's their continent, right?" Rubio said.

Rubio, a former senator once known as a more traditional Republican with hawkish views on Russia and China, cast Trump's cajoling of European allies to spend more on defense as consistent with long-standing calls from the United States across administrations.

Trump has spoken dismissively in the past of the transatlantic alliance and stunned many in Europe by reaching out to Russian President Vladimir Putin to seek a deal on Ukraine, which Moscow invaded three years ago.

On Monday, the United States sided with Russia and against nearly all of its European allies with a United Nations resolution that urged an end to the Ukraine war without emphasizing the country's territorial integrity.

Merz, a conservative, said after his election victory that he wanted good ties with the United States but added that Trump made clear that US interest in Europe was fading.

Pointing to Trump's comments, Merz said that Europe must move quickly to "achieve independence" from the United States on defense matters.