President Biden announced Monday that the U.S. had killed with a drone strike one of the masterminds behind the 9/11 attacks, al Qaeda leader Ayman al-Zawahiri. Mark Jacobson, assistant dean for Washington Programs and former deputy NATO Afghanistan adviser, joined CBS News Mornings with analysis.

"One of the assumptions of the Biden administration during the withdrawal from Afghanistan was that al Qaeda and other groups—ISIL for example—wouldn't pose a threat to the United States," says Jacobson. "Part of that is the degree to which the Taliban were allowing these groups to take residence without any repercussions," he says.

"And it's no surprise to most people who've been watching the situation for two decades now, that the Taliban allowed someone like al-Zawahiri to stay. The question is, who else? How much will al Qaeda be able to grow in an Afghanistan that is essentially ungoverned now and to the degree there is someone in control, someone who has been in the past, friendly towards al Qaeda," Jacobson says.

Watch the full interview via CBS News Mornings.