'What is Aleppo?' US presidential candidate's ignorance stuns Twitter

A US presidential candidate stunned the hosts of a TV news show on Thursday when he asked "What is Aleppo?" in response to a question about the battlefront Syrian city.

Libertarian White House contender Gary Johnson appeared utterly clueless when asked about his proposal to solve the Aleppo crisis should he be elected head of state in November.

"What would you do if you were elected, about Aleppo?" journalist Mike Barnicle asked Johnson on MSNBC's "Morning Joe" programme.

"About?" Johnson responded.

"Aleppo," replied Barnicle.

"And what is Aleppo?" asked Johnson.

"You're kidding," responded Barnicle.

"No," said Johnson.

Barnicle went on to explain, in seeming disbelief, that Aleppo was the "epicentre of the refugee crisis".

After the clarification, the presidential candidate offered up that Syria was a "mess" and that only way to deal with the five-year bloody civil war was to partner with Russia.

A Washington Post-Survey Monkey poll released on Wednesday found that Johnson, who is hardly ever included in presidential polling, is supported by an average of 13 percent across all states.

Soon after Johnson's gaffe went viral he issued an online statement claiming he "blanked" during the interview, adding, "It happens and it will happen again during the course of this campaign."

Once Syria's commercial powerhouse, Aleppo is now a divided city, with rebel groups firing into the government-held west and regime and allied Russian warplanes pounding the opposition-controlled east.

The hashtag #WhatIsAleppo began trending on Twitter soon after Johnson made his remarks comment, as people weighed in with sarcasm and disbelief.