Afghanistan: Why can't the UK hold Kabul airport without the US?

The UK is set to ask the US to extend its deadline for leaving Afghanistan, to allow more rescue flights.

UK ministers said they can't continue to evacuate people at Kabul airport without the US presence.

The US is providing the bulk of the troops to keep the airport secure and is running many of its facilities - including air traffic control.

The US is also providing intelligence and surveillance for the operation - which would take significant time and resources to replace.

General Sir Richard Barrons, commander Joint Forces Command from 2013 until 2016, said carrying out evacuations without US support would be extremely difficult.

"We would have to be prepared to leave the airport, and fight the Taliban to go and get these people. I just don't see that as a credible proposition.

"And secondly, if the Taliban don't want our aeroplanes to use the airport, one mortar round, one missile, one burst of machine gun fire, and the evacuation is over."

Protection from fighter jets or helicopters is vital, according to Nick Reynolds of the Royal United Services Institute think tank. The US is currently providing this.

And the RAF's limited number of transport aircraft, means the UK does not have the capability "to conduct an effective evacuation by itself, especially not under time pressure", he said.

American troops are currently the largest presence at Hamid Karzai International Airport, with around 6,000 present.

There have been American jets patrolling the skies, as well as attack helicopters present.

The UK has more than 1,000 at the airport, including the Army's 16 Air Assault Brigade.

Smaller contingents from Nato members including France, Germany and Turkey are also present.

Norway has also been playing a role, with a hospital at the airbase.

Nato has said it had around 800 civilian contractors on the ground - most of them at the airport.

UK Prime Minister Boris Johnson is expected to urge US President Biden to postpone the planned 31 August withdrawal, during an emergency meeting of G7 leaders on Tuesday.

On Monday, armed forces minister James Heappey said about 1,800 "eligible people" or UK passport holders remained in Afghanistan.

He said there were also 2,275 Afghans who can be resettled having worked for the UK government, and more people from "wider Afghan civil society who we would like to get out if we're able".

But Defence Secretary Ben Wallace has made clear that when American forces leave Kabul, "we will have to leave as well".

But on Sunday he said: "Our hope is we will not have to extend."

The positions of the UK and US reflect their different priorities, according to Nick Reynolds.

He said the UK wants to "evacuate as many people as possible", with the timetable "a secondary concern". Sticking to the 31 August deadline was a "higher priority" for the US, he said.

So far, the Taliban has been co-operating - marshalling people into queues at the airport.

But a spokesperson said the 31 August deadline for withdrawal was a"red line" .

The spokesperson said President Biden had said troops would be out by that date, and staying longer meant extending Afghanistan's occupation. He warned of consequences if that were to happen.