The United States has started formally withdrawing troops from Afghanistan after first arriving 20 years ago.
President Joe Biden set 1 May as the official start of the withdrawal of the remaining forces - up to 3,500 US troops and about 7,000 NATO soldiers.
The military has been taking inventory, deciding what is shipped back to the US, what is handed to the Afghan security forces and what is sold as junk in Afghanistan's markets. In recent weeks, the military has been flying out equipment on massive C-17 cargo planes.
The US is estimated to have spent more than $2 trillion USD in Afghanistan in the past two decades, according to the Costs of War project at Brown University, which documents the hidden costs of US military engagement.
Australia will withdraw its final troops from Afghanistan, Prime Minister Scott Morrison announced last month.
The US and its NATO allies went into Afghanistan in 2001 to hunt the al-Qaeda perpetrators of the September 11 terrorist attacks who lived under the protection of the country's Taliban rulers. Two months later, the Taliban had been defeated and al-Qaeda fighters and their leader, Osama bin Laden, were on the run.
US Navy SEALS killed bin Laden a decade ago, at his hideout in neighbouring Pakistan. Since then, al-Qaeda has been degraded, while the terrorist threat has "metastasised" into a global phenomenon that is not contained by keeping thousands of troops in one country, Mr Biden said in his withdrawal announcement last month.
Afghans have paid the highest price since 2001, with 47,245 civilians killed, according to the Costs of War project. Millions more have been displaced inside Afghanistan or have fled to Pakistan, Iran and Europe.
Afghanistan's security forces took heavy losses of some 66,000 to 69,000 troops.
2,442 US troops have been killed and 20,666 wounded since 2001. It is estimated that over 3,800 US private security contractors have been killed, but the Pentagon does not track their deaths.
The conflict also killed 1,144 personnel from NATO countries.
Afghanistan's security forces are expected to come under increasing pressure from the Taliban after the withdrawal if no peace agreement is reached in the interim, according to Afghan watchers.
The Taliban, meanwhile, are at their strongest since being ousted in 2001.
"We are telling the departing Americans ... you fought a meaningless war and paid a cost for that and we also offered huge sacrifices for our liberation," Taliban spokesman Suhail Shaheen told the AP on Friday.
Striking a more conciliatory tone, he added: "If you ... open a new chapter of helping Afghans in reconstruction and rehabilitation of the country, the Afghans will appreciate that."
