US presidential candidate Gary Johnson: 'What is Aleppo?'

Libertarian US presidential candidate Gary Johnson was left stumped when he was asked a question on the situation in Syria.

During an appearance on MSNBC's "Morning Joe", Mr Johnson was asked by Mike Barnicle what he would do if elected president, about Aleppo.

"And what is Aleppo?" Johnson replied

"You're kidding," Mr Barnicle responded, before explaining that it is a city in Syria.

"It's the epicentre of the refugee crisis," he added.

"OK, got it, got it," Mr Johnson interrupted and then added: "With regard to Syria I do think it's a mess.

"I think that the only way that we deal with Syria is to join hands with Russia to diplomatically bring that at an end."

After the recording and away from the studio, Mr Johnson was asked whether he should have known more about Aleppo.

He appeared flustered, and awkwardly bumbled his way through the question.

"When you recognise what's going on in Syria, when you recognise that Aleppo is in the epicentre... Aleppo... not knowing there's a city in between... the two forces... really at the epicentre of the... but not remembering or identifying that that's Aleppo... guilty."

"I'm incredibly frustrated with myself," he added, before admitting his embarrassing interview should be regarded as a "big flap".

"I understand the significance, believe me, no-one is taking this more seriously than me. I feel horrible. I have to get smarter."