All U.S. forces have now left Bagram Air Base in Afghanistan, and CNN takes a look at what happens next.

"The Bagram exit was without pomp and ceremony," Poppy Harlow said.

"It is seen as a symbolic victory for the Taliban, who have been gaining significant ground in Afghanistan as the United States leaves. Our Anna Coren is there. It leaves question marks and danger for those on the ground in Afghanistan. I'm talking about Afghans."

Coren said it's a "huge" vacuum, and there's no guarantee Afghanistan won't once again become a safe haven for terrorists.

"So much blood and treasure has been spent here in this country. $2 trillion. More than 2,400 u.s. lives, more than 100,000 Afghan lives, tens of thousands of Afghan soldiers have died on the battlefield and continue to die. We know the security situation is deteriorating as the Taliban launches its offensive across the country, particularly in the north gaining ground every day. But it had to come to an end. U.S. President Joe Biden, he brought forward the date. It was September 11, and now, you know, as of today and overnight, three planeloads flew out of U.S. and NATO forces.

"We know that General Scott Miller met with the president of Afghanistan to discuss America's ongoing assistance. And we know that America is not abandoning Afghanistan. They pledged $3.3 billion to provide security assistance in the coming year. And they are going to need it. We spoke to Dr. Abdullah Abdullah, who is head of the peace talks between the Afghan government and the Taliban, and he says if it was up to the Afghans, the Americans would not have left. That now is not the right time because of the insurgency, because of the gains the Taliban are making. It's time for Afghan forces to step up.

"Bagram Air Field was passed over to the Afghans today. There are 4,000 Afghan security forces in place at Bagram Air Field. but there is no denying, Poppy, that America leaves Afghanistan, you know, not strong, prosperous and stable, but rather in a very precarious situation after 20 years in country."