WASHINGTON — US President Joe Biden said the US is on track to meet its target of removing American combat troops from Afghanistan ahead of the original deadline of Sept. 11, as a near-complete withdrawal of American troops is coinciding with major Taliban gains.

Biden said American troops will be done with the military mission in the US' longest war by Aug. 31. He said the US went into Afghanistan to prevent another terrorist attack on the scale of the tragedies on Sept.11, 2001, and the military accomplished that mission.

"We achieved those objectives, that's why we went. We did not go to Afghanistan to build the nation, and it's the right and responsibility of the Afghan people alone to decide their future and how they want to run their country," Biden said.

Facing the prospect of a Taliban takeover within a year — accompanied, most likely, by devastation and suffering — Biden aimed to convey continued support for the country. White House officials say he will detail US security and humanitarian assistance that will carry on once the troop presence ends.

He also directly addressed the thousands of Afghans who assisted the United States during the war who are now waiting on their US visa applications, senior administration officials said. He has been under pressure to detail how exactly he will ensure the safe passage of Afghan translators and other workers who assisted American forces during the war and are now targets for the Taliban.

Biden has vowed to allow those who helped the US effort to come to the United States, but the visa process has been slow, leading officials to develop plans to relocate them to a third country. Officials said Biden will discuss plans to begin relocating those Afghans in August.

The deteriorating security situation in Afghanistan, while troubling, has not deterred Biden from pushing ahead with his plans to bring US troops home.

Instead, the pace with which the Taliban have gained ground in recent weeks has, in a way, only solidified for the White House the merits of Biden's decision, according to multiple officials, who said it has made clear the limited value of a long-term force presence.

Last week, Biden bristled under questioning on Afghanistan, saying he'd rather discuss the matter after the July 4 holiday.

"It's a rational drawdown with our allies — there's nothing unusual about it," Biden said on Friday of the pace of withdrawal, which has caught some in Washington by surprise.

He said he had faith in the civilian leaders in Kabul, whom he met in the Oval Office last month, despite American intelligence assessments the capital could fall to the Taliban in as little as six months after US troops depart. But he said the fractious divides within the government must be resolved.

"I am concerned that they deal with the internal issues that they have to be able to generate the kind of support they need nationwide to maintain the government," Biden said.

The withdrawal has proceeded quickly after Biden announced in April he would wind down America's presence in Afghanistan by Sept. 11, the 20th anniversary of the terror attacks that prompted the war.

Officials recently began citing an earlier date — late August — by which the last remaining troops would exit the country, with a small contingent left behind to protect diplomatic facilities.

The withdrawal is now more than 90 percent complete, officials say. The last US troops left Bagram Air Base last week, marking the end of the American presence at the sprawling compound that became the center of military power in Afghanistan. — CNN