Chairman of the Joint Chiefs of Staff Gen. CQ Brown said Monday that “US credibility is at stake” in the wake of comments from former President Donald Trump that he would encourage Russia to “do whatever the hell they want” to NATO partners that don’t meet spending guidelines on defense.

Asked by “NBC Nightly News” about Trump’s admission that he would not abide by the collective-defense clause at the heart of NATO if reelected, Brown said that the alliance is strong and has been around for 75 years.

“I think we have a responsibility to uphold those alliances,” Brown told NBC’s Lester Holt in an interview airing Monday evening. “US credibility is at stake with each of our alliances, and US leadership is still needed, wanted, and watched.”