WASHINGTON — Facing sharp criticism over the tumultuous United States (US) withdrawal from Afghanistan, President Joe Biden said on Tuesday (Aug 31) it was the best available option to end both the US' longest war and decades of fruitless efforts to remake other countries through military force.

Mr Biden portrayed the chaotic exit as a logistical success that would have been just as messy even if it had been launched weeks earlier, while staying in the country would have required committing more American troops.

"I was not going to extend this forever war," he said in a speech from the White House.

Earlier in the day, the Taliban, which seized control of Afghanistan in a lightning advance this month, celebrated their victory. They fired guns into the air, paraded coffins draped in US and North Atlantic Treaty Organization flags and set about enforcing their rule after the last US troops withdrew.

In his first remarks since the final pullout on Monday, Mr Biden said 5,500 Americans had been evacuated and that the US had leverage over the Islamist militant group to ensure 100 to 200 others could also depart if they wanted to.

He said Washington would continue to target militants in the country who posed a threat to the US, but would no longer use its military to try to build cohesive, democratic societies in places that have never had them.

"This decision about Afghanistan is not just about Afghanistan. It's about ending an era of major military operations to remake other countries," he said.

The Taliban now control more territory than when they last ruled before being ousted in 2001 at the start of America's longest war, which took the lives of nearly 2,500 US troops and an estimated 240,000 Afghans, and cost some US$2 trillion (S$2.7 trillion).

More than 123,000 people were evacuated from Kabul in a massive but chaotic airlift by the US and its allies over the past two weeks, but many of those who helped Western nations during the war were left behind.

Mr Biden said the only other option would have been to step up the fight and continue a war that "should have ended long ago." Starting the withdrawal in June or July, as some have suggested, would only have hastened the Taliban's victory, he said.

But Mr Biden's decision is far from popular: 51 per cent of Americans disapprove of his approach to the pullout and only 38 per cent support it, according to Reuters/Ipsos polling. He has faced criticism from Republicans and fellow Democrats, as well as from foreign allies.

US Senate Republican leader Mitch McConnell said the departure had abandoned Americans behind enemy lines.

"We are less safe as a result of this self-inflicted wound," he said in his home state of Kentucky.

ELATION AND FEAR

In Afghanistan, there was a mixture of triumph and elation on the one side as the Taliban celebrated their victory, and fear on the other.

"We are proud of these moments, that we liberated our country from a great power," Taliban spokesman Zabihullah Mujahid said at Kabul airport after a C-17 aircraft took the last US troops out a minute before midnight.

While crowds lined the streets of the eastern city of Khost for a mock funeral with coffins draped with Western flags, long lines formed in Kabul outside banks closed since the fall of the capital.

"I had to go to the bank with my mother but when I went, the Taliban (were) beating women with sticks,” said a 22-year-old woman who spoke on condition of anonymity because she feared for her safety.

She said the assault occurred among a crowd outside a branch of the Azizi Bank next to the Kabul Star Hotel in the centre of the capital. "It’s the first time I’ve seen something like that and it really frightened me."

Mr Biden has said the world would hold the Taliban to their commitment to allow safe passage for those wanting to leave Afghanistan in future, and to uphold human rights.

Separately, he signed legislation to provide aid to Americans returning from Afghanistan. European Union countries proposed to step up assistance to Afghanistan and its neighbours.

The US invasion in 2001, which followed the Sept 11 attacks on New York and Washington, stopped Afghanistan from being used by Al Qaeda as a base to attack the US and ended a period of Taliban rule from 1996 in which women were oppressed and opponents crushed.

Mr Zabihullah said the group wanted to establish diplomatic relations with the world, but Germany reiterated that the Taliban needed to set up an inclusive government if they are to get aid.

"The international community also demands certain prerequisites for this," German Foreign Minister Heiko Maas said.

Destruction from recent fighting and a hiatus in administration and the foreign aid on which many Afghans depend have left the country in a precarious state, and the Taliban do not have complete control.

At least seven Taliban fighters were killed in clashes in the Panjshir valley north of the capital on Monday night, two members of the main anti-Taliban opposition group said.

Thousands of Afghans have already fled the country, fearing Taliban reprisals.

Pentagon spokesman John Kirby said the US military was not concerned by images of Taliban members walking through Kabul airport holding weapons and sizing up US helicopters.

But he said the US was concerned about the potential for Taliban retribution and mindful of the threat posed by Isis-K, the Islamic State affiliate that claimed responsibility for a suicide bombing outside Kabul airport on Thursday that killed 13 US service members and scores of Afghan civilians. REUTERS