Scarborough learned of the exchange “in the last few days,” according to an MSNBC executive.

Trump campaign chairman Paul Manafort denied the claim on Wednesday morning.

“Absolutely not true,” he said in an interview with Fox News. “The idea that he’s trying to understand where to use nuclear weapons? It just didn’t happen. I was in the meeting, it didn’t happen.”

In March, Trump refused to rule out using tactical nuclear weapons in the war against the so-called Islamic State.

“I’m never going to rule anything out — I wouldn’t want to say. Even if I wasn’t, I wouldn’t want to tell you that because at a minimum, I want them to think maybe we would use them,” he said in an interview with Bloomberg Politics.

In a followup interview with MSNBC’s Chris Matthews, Trump sounded unconcerned by the prospect of mutual assured destruction, going so far as to ask why the U.S. constructed nuclear weapons if it couldn’t use them.

“Then why are we making them? Why do we make them?” he asked.

“I was against Iraq. I’d be the last one to use them,” he added. (Trump initially supported the Iraq invasion.)

This post was updated with a statement from Paul Manafort.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims ― 1.6 billion members of an entire religion ― from entering the U.S.