Republican presidential nominee Donald Trump asked a foreign policy advisor why the US could not use nuclear weapons, MSNBC host Joe Scarborough claimed on air on Wednesday (3 August). Scarborough cited an unnamed source who claimed to have spoken to Trump.

"I'll have to be very careful here. Several months ago, a foreign policy expert on the international level went to advise Donald Trump, and three times he asked about the use of nuclear weapons. Three times he asked, at one point, if we had them, why can't we use them," Scarborough said during his Morning Joe programme.

He continued: "That's one of the reasons he just doesn't have foreign policy experts around him. Three times, in an hour briefing, why can't we use nuclear weapons."

According to CNBC, Scarborough made the remarks less than a minute into the interview with former Director of Central Intelligence and ex-National Security Agency Director Michael Hayden. The host then asked Hayden a hypothetical question about how quickly nuclear weapons could be deployed after a president's approval.

"It's scenario dependent, but the system is designed for speed and decisiveness. It's not designed to debate the decision," Hayden answered. Hayden also told Scarborough that what concerned him most of the GOP nominee was "how erratic he is".

Trump campaign chairman Paul Manafort later denied the claim. "Absolutely not true," Manafort 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."

The Huffington Post noted that in March Trump refused to rule out using nuclear weapons against the Islamic State (Isis). "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 told Bloomberg Politics at the time.