WASHINGTON - The United States expects to finish withdrawing its troops from Afghanistan by the end of August, officials said Friday, after announcing all American and NATO soldiers had left the conflict-scarred nation's biggest air base.

Following 20 years of war, US President Joe Biden had set a September 11 deadline for the final pullout of the few remaining soldiers on the ground.

The news Friday that American troops had left Bagram Air Base fueled expectations that the pullout would be completed within days, but White House Press Secretary Jen Psaki said the troops would be out of the country "by the end of August."

"The president has long felt... that the war in Afghanistan was not one that can be won militarily," she told reporters, adding that the United States would continue to provide security systems and humanitarian assistance in the months ahead.

Bagram served as the linchpin for US-led operations in the rugged country, where the long war against the Taliban and their Al-Qaeda allies started in 2001 following the September 11 attacks.

"The American and coalition forces have completely withdrawn from the base and henceforth the Afghan army forces will protect it and use it to combat terrorism," defense ministry spokesman Fawad Aman tweeted.

A US defense official confirmed their departure, while the Taliban said it welcomed the latest phase of the pullout.

"Their full withdrawal will pave the way for Afghans to decide about their future between themselves," spokesman Zabihullah Mujahid said.

One Afghan official said some local thugs and drug addicts attempted to loot equipment at the base, but were stopped by Afghan troops.

"There will be no lootings as long as we are here... we will defend and protect our country," said Alifullah, an Afghan soldier guarding one of the base's gates.

The US military and NATO are in the final stages of winding up involvement in Afghanistan, bringing home an unspecified number of remaining troops by Biden's deadline.

The Taliban have launched relentless offensives across Afghanistan in the past two months, gobbling up dozens of districts as Afghan security forces have largely consolidated their power in the country's major urban areas.

The ability of Afghan forces to maintain control of Bagram airfield will likely prove pivotal to maintaining security in Kabul and keeping pressure on the Taliban.

The exit of foreign forces from Bagram base "symbolizes that Afghanistan is alone, abandoned, and left to defend itself against the Taliban's onslaught", said Australia-based Afghanistan expert Nishank Motwani.

"Having reached home, Americans and allied forces will now watch what they fought so hard to build over 20 years burn down from afar and knowing that the Afghan men and women they fought with risk losing everything."

AFP