VIDEO: Khorasan Group posed imminent threat

WASHINGTON (KABC) -- ISIS wasn't the only target; one-third of the U.S.-led airstrikes were aimed at a little known al Qaeda-affiliated terror group known as the Khorasan Group.

U.S. officials say the Khorasan Group is a network of al Qaeda veterans working out of Syria to develop external attacks. Many of the seasoned fighters were close to Osama Bin Laden. The group may have been planning a Sept. 11 style attack on the United States.

A senior law enforcement source tells ABC News they were about to enter the execution phase of their attack, which led to a massive bombing campaign from the U.S.

Retired Lt. Col. Hal Kempfer of the U.S. Marine Corps Reserve tells Eyewitness News what he knows about the mysterious Khorason Group.

Watch the video above on Eyewitness News above.