After seizing much of the country in the last several weeks, Taliban militants now surround the Afghan capital of Kabul. Carter Malkasian, a former senior adviser to the chairman of the US joint chiefs of staff, says there are a couple of reasons for the armed group's rapid advancement.
"Afghan forces, for a long period of time, have had problems with morale and also their willingness to fight the Taliban," Malkasian, who is also the author of "The American War in Afghanistan: A History," told CNN on Sunday.
"First of all, the Taliban can paint themselves as those who are resisting and fighting occupation, which is something that is kind of near and dear to what it means to be Afghan. Whereas that's a much harder thing for the government to claim, or the military forces forces fighting for the government."
He also said the Taliban's repeated successes in taking provincial cities will have impacted the confidence of Afghan security forces. "There's no doubt that morale suffers when forces face defeat after defeat," he continued.
"The more defeats that are suffered, the worst morale is going to get, so they've been suffering this kind of chain reaction for, really, the past three months. And on the other side of the fence, the Taliban are getting emboldened by success after success, and these kind of compounding effects make it even harder for the Afghan forces to hold ground."