WASHINGTON - President Joe Biden announced Wednesday it's "time to end" America's longest war with the unconditional withdrawal of troops from Afghanistan, where they have spent two decades in a bloody, largely futile battle against the Taliban.

Dubbed the "forever war," the US military onslaught in Afghanistan began in response to the September 11, 2001 attacks against the United States.

Now, 20 years later -- after almost 2,400 US military and tens of thousands of Afghan deaths -- Biden named September 11 as the deadline by which the last US soldiers will have finally departed.

In a nationally televised address, Biden said the United States had accomplished its limited original mission of crushing the international jihadist groups behind the 9/11 attacks and that with every passing year the rationale for staying was "increasingly unclear."

Biden insisted there would be no "hasty exit," but he was adamant about his decision.

"A horrific attack 20 years ago... cannot explain why we should remain there in 2021," he said. "It's time to end the forever war."

The conflict is at best at a stalemate. The internationally backed government in Kabul has only tenuous control in swaths of the country, while the Taliban are growing in strength, with many predicting the insurgency will seek to regain total power once the government's US military umbrella is removed.

Biden told Americans that it was time to accept the reality that there's no alternative.

"We cannot continue the cycle of extending or expanding our military presence in Afghanistan hoping to create the ideal conditions for our withdrawal, expecting a different result," he said.

"I am now the fourth American president to preside over an American troop presence in Afghanistan. Two Republicans. Two Democrats," he said. "I will not pass this responsibility to a fifth."

Biden's decision was not a shock. The war is hugely unpopular among voters and Biden's predecessor Donald Trump had committed to pulling out at the start of May.

"I applaud President Biden's decision," top Democratic Senator Chuck Schumer said Wednesday.

However, there was immediate criticism from some quarters that the United States is abandoning the Afghan government and encouraging jihadist insurgencies.

"We're to help our adversaries ring in the anniversary of the 9/11 attacks by gift wrapping the country, and handing it right back to them," senior Republican Senator Mitch McConnell said.

Immediately after the speech, an emotional Biden walked under light rain through Arlington National Cemetery, and told reporters that his decision had not been difficult.

"It was absolutely clear, absolutely clear," he said.

AFP