Rep. Adam Schiff, a Democratic member of the House Permanent Select Committee on Intelligence, said “we have been briefed on the Khorasan group for some time.”

“I knew about the group a year ago from the media but didn’t know the name or personalities until the past few days—again from the media,” said Will McCants, a terrorism analyst and fellow at the Brookings Institution.

An Amnesty International report on drones in Pakistan from October 2013 refers to an “al-Qa’ida-linked outfit” called Mujahideen Khorasan, but is unclear if it’s the same Khorasan. A source that was briefed on Khorasan in June said that the counterterrorism community believes that between 10 and 20 top Al Qaeda people had gone to Syria from Waziristan “to link up in Syria and establish a new AQ affiliate in Syria that would be focused on training and deploying against the West.”

“The group has been referred to elliptically in open-source reporting for several months now,” said Daveed Gartenstein-Ross, a counter-terrorism analyst at the Foundation for Defense of Democracies. Gartenstein-Ross said that the composition and size of the group is still unclear, though: “At the very least, number one, it’s embedded with Jabhat al-Nusra but it’s a separate organization from Nusra.” The name, he said, “has particular eschatological meanings related to jihadist views of the end times.”