image copyrightAFPimage captionThe US air force was still using Bagram on Thursday

The last US and Nato forces have left Bagram airbase in Afghanistan, the epicentre of the war against the Taliban and al-Qaeda for some 20 years.

The pull-out could signal that the complete withdrawal of foreign forces from Afghanistan is imminent.

President Joe Biden has said US forces will be gone by 11 September.

But the withdrawal from the sprawling base, north of Kabul, comes as Taliban insurgents continue to advance in many parts of Afghanistan.

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The 11 September deadline is the anniversary of the al-Qaeda attacks on America in 2001, which killed nearly 3,000 people and sparked the US-led invasion of Afghanistan.

Some 2,500-3,500 US troops were thought to be still in Afghanistan until recently, and they are due to leave along with some 7,000 allied foreign troops.

One of the remaining missions of the combined force is to protect the international airport of the Afghan capital, Kabul, as talks continue on its future security.

Taliban militants have overrun dozens of districts, amid fears that a new civil war could erupt after the departure of foreign forces.

.. the last of US & other NATO forces have now left #Bagram base .. Bagram is also a town where #Afghans now wonder and worry about their future .. including these school girls whose path goes past the base ..#Afghanistan

— lyse doucet (@bbclysedoucet) July 2, 2021
The BBC is not responsible for the content of external sites.View original tweet on TwitterHow big is Bagram Airfield?

The airfield, originally built by the Soviet military during its occupation of Afghanistan in the 1980s and named after a nearby village, lies around 40km (25 miles) north of Kabul.

The US-led coalition forces moved in during December 2001, and it was developed into a huge base capable of holding up to 10,000 troops.

It is served by two runways, the most recent of which is 3.6km long, where large cargo and bomber aircraft can land.

It has 110 parking spots for aircraft, which are protected by blast walls, and had a 50-bed hospital with a trauma bay, three operating theatres and a modern dental clinic, the Associated Press reports.

media captionFrom May 2021: Top US commander General Scott Miller reflects on Nato forces' time in Afghanistan ahead of its departure

Its hangars and buildings included the main prison facility for people detained by US forces at the height of the conflict, which became known as Afghanistan's Guantanamo – after the infamous US military prison in Cuba.

Bagram was one of the sites identified in a US Senate report on the CIA's interrogation of al-Qaeda suspects, including the use of torture, carried out in detention facilities.

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