Nearly twenty full years after the United States led invasion, the extremist group is viewed as an even bigger threat than the Taliban rightly so because of its growing sophisticated military prowess and its strategy of targeting civilians, both in Afghanistan and abroad. Deep concerns run so wide that many have come to see the Taliban, which has also clashed with IS, as a potential partner in containing it.

A United States intelligence official based in Afghanistan reported to The Associated Press that a recent wave of attacks in the capital, Kabul, is “practice runs” for even greater attacks in Europe and the United States.

“This group is the most near-term threat to our homelands from Afghanistan,” the official said on condition of anonymity to preserve his operational security. “The IS core mandate is: You will conduct external attacks” in the U.S. and Europe. “That is their goal. It’s just a matter of time,” he said. “It is very scary.”

The director of the Center for Security Studies at Georgetown University, Bruce Hoffman, sees Afghanistan as a very likely new base for IS now that it has been driven from Iraq and Syria. “ISIS has invested a disproportionate amount of attention and resources in Afghanistan,” he said, pointing to “huge arms stockpiling” in the east.