“With Putin I said, ‘If you go into Ukraine, I’m going to bomb the sh*t out of Moscow. I’m telling you I have no choice,’” Trump said during one 2024 fundraiser, according to the audio. “And then [Putin] goes, like, ‘I don’t believe you.’ But he believed me 10%.”
“Trump later claimed he relayed a similar warning to Chinese President Xi Jinping over a potential invasion of Taiwan, telling him that the US would bomb Beijing in response” https://www.cnn.com/2025/07/08/politics/trump-tape-putin-bomb-fundraiser?cid=ios_app

Trump said he threatened to bomb Moscow if Putin attacked Ukraine, 2024 fundraiser tapes show
Donald Trump told a private gathering of donors last year that he once sought to deter Russian President Vladimir Putin from attacking Ukraine by threatening to “bomb the sh*t out of Moscow” in retaliation, according to audio provided to CNN.