Puzzled US Presidential Candidate Gary Johnson Asks: What Is Aleppo?

US presidential candidate Gary Johnson stunned the hosts of a news show when he asked: "What is Aleppo?"

The Libertarian Party contender was responding to a question on MSNBC's Morning Joe show about the Syrian city ravaged by the country's civil war.

Journalist Mike Barnicle, who had asked Johnson what he would do about the Aleppo crisis if elected, replied with an incredulous "you're kidding me".

He then explained: "Aleppo is in Syria. It's the epicentre of the refugee crisis."

Following the clarification, Johnson said: "Okay, I got it... With regard to Syria, I do think it's a mess."

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

Johnson, a former two-term governor of New Mexico, is seeking inclusion in upcoming presidential debates against Democrat Hillary Clinton and Republican Donald Trump.

To do that he needs the backing of 15% of voters, but a recent Washington Post-Survey Monkey poll found he only has 13%.

The hashtag #WhatIsAleppo began trending on Twitter soon after Johnson's comment as members of the public weighed in with sarcasm and disbelief.

"You hear that? That's the sound of Gary Johnson's campaign coming to a crashing halt," tweeted one user.

Another speculated that Aleppo "was one of the Marx Brothers, right?"

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 jets pounding the opposition-controlled east.

On Wednesday, strikes by unidentified aircraft on the eastern Sukkari district left 11 civilians dead, according to the Syrian Observatory for Human Rights.

Earlier this week, activists claimed government warplanes dropped bombs laced with chlorine gas on a rebel-held area of Aleppo.

A volunteer rescue group called Syrian Civil Defence said they fell in the al Sukkari neighbourhood and at least 80 people including children were sent to hospitals suffering from asphyxia.

Hundreds of thousands of people have been killed in Syria's five-year conflict, while 11 million people, half the pre-war population, have been displaced.