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.
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.
Meanwhile, Taliban militants have advanced in different parts of the country, overrunning dozens of districts, amid fears that a new civil war could erupt after the departure of foreign forces.