The US has started formally withdrawing troops from Afghanistan, beginning the end of what President Joe Biden called “the forever war”.
The US and Nato have had a presence in Afghanistan for almost 20 years.
On Friday, Afghanistan, the US, China, Russia and Pakistan called for peace during the withdrawal, which is set to continue until 11 September.
Security forces in Afghanistan are on high alert for any attempted attacks on retreating US and Nato troops.
Why are US forces in Afghanistan?
On 11 September 2001, attacks in America killed nearly 3,000 people. Osama Bin Laden, the head of Islamist terror group al-Qaeda, was quickly identified as the man responsible.
The Taliban, radical Islamists who ran Afghanistan and protected Bin Laden, refused to hand him over. So, a month after 9/11, the US launched air strikes against Afghanistan.
As other countries joined the war, the Taliban were quickly removed from power. But they didn’t just disappear – their influence grew back and they dug in.
Since then, the US and its allies have struggled to stop Afghanistan’s government collapsing, and to end deadly attacks by the Taliban.
The violence is still going on, right?
The withdrawal of US troops begins against a backdrop of fierce clashes between the Taliban and government forces, in the absence of a peace deal.
A flare up of violence in Ghazni province overnight left an unknown number of people dead.
And on Friday, a car bombing in Pul-e-Alam, Logar province, killed at least 24 people and wounded 110 – mostly school pupils.
US President Joe Biden says the US pull-out is justified as US forces have made sure the country cannot again become a base for foreign jihadists to plot against the West.
And Afghan President Ashraf Ghani says government forces are fully capable of keeping insurgents at bay.
He has argued that withdrawing US and Nato forces will remove the Taliban’s reason for fighting, saying to the Taliban: “Who are you killing? What are you destroying? Your pretext of fighting the foreigners is now over.”
But many do not share the optimism.
“Everyone is scared that we might go back to the dark days of the Taliban era,” Mena Nowrozi, who works at a private radio station in Kabul told news agency AFP.
“The Taliban are still the same; they have not changed. The US should have extended their presence by at least a year or two.”
BBC Pakistan and Afghanistan correspondent Secunder Kermani says that with peace talks between the militants and Afghan government stalled, despite the drawing down of international involvement, it seems inevitable the conflict will continue.
What is the symbolism of the timing?
US forces were originally slated to leave by 1 May under a deal agreed with the Taliban in 2020, but President Biden pushed the deadline back – a move that the Taliban have criticised.
The Taliban’s spokesman said America’s delay in the withdrawal timetable broke the terms of the agreement and meant militants were no longer bound by an undertaking not to attack foreign forces.
Mr Biden said last month that the withdrawal will be completed by 11 September – the 20th anniversary of the 9/11 attacks.
The 1 May is also a significant date, marking 10 years to the day since the US announced it had killed Osama Bin Laden, following a special forces raid on his compound in Abbottabad, Pakistan.