Biden says US military mission in Afghanistan will conclude Aug. 31

"The drawdown is proceeding in a secure and orderly way, prioritizing the safety of our troops as they depart," Biden said at a news conference.

White House spokeswoman Jen Psaki said earlier that the war in Afghanistan has not been won military by any party as the US withdrawal continues.

"We're not going to have a mission accomplished moment" in Afghanistan, she added.

The president said it is "highly unlikely" a unified government will control Afghanistan after the US pullout as he pushed for a deal with the Taliban.

Asked if the 20-year was worth it for the US to be militarily present there, Biden said he was opposed to permanently having American forces in Afghanistan and no nation has been unified on Afghanistan.

He said the US was in Afghanistan for two reasons: to take down Al-Qaeda leader Osama bin Laden and eliminate the group's ability to attack the US.

"We've accomplished both of these objectives. Period," said Biden.

US Central Command (CENTCOM) said Tuesday that the process to withdraw American forces from Afghanistan by September is more than 90% complete.

A trillion dollars has been spent training and equipping hundreds of thousands of Afghan forces, he said, and a total of 2,448 Americans were killed and 20,722 more wounded during the US' longest war.

"I will not send another generation of Americans to war in Afghanistan," he said.

When asked if he trusted the Taliban, he said, "No," and added that their takeover of Afghanistan is "not inevitable" after US forces pull out.

"I trust the capacity of the Afghan military, who is better trained, better equipped and more competent in terms of conducting war," he added.