Despite al-Zawahiri strike, US officials are concerned about terrorism threats in Afghanistan

Shortly before the US withdrawal from Afghanistan, the Defense Department created a task force responsible for handling counterterrorism strikes inside the country after American troops had left -- a so-called "over the horizon" strategy that officials promised would keep Afghanistan from once again becoming a safe haven for terror groups like al Qaeda and ISIS to flourish.

More than a year after the creation of that task force, sources say it hasn't sent a single proposed target to the Pentagon for approval -- largely because without a presence on the ground, it hasn't been able to build enough intelligence on targets to meet the administration's standards for avoiding civilian casualties.

The White House has hailed the CIA operation that killed al Qaeda leader Ayman al-Zawahiri in Kabul on Saturday as evidence that using over the horizon counterterrorism capabilities in Afghanistan has been effective. Current and former officials say the successful Zawahiri strike certainly proves that with the right intelligence, the US is perfectly capable of tackling a specific target from afar -- but those same sources also said that Zawahiri, a single, high-value target long in the CIA's crosshairs, was a special case that doesn't alone prove the effectiveness of the strategy.