A third member of the team was knocked unconscious and shredded by ball bearings when a teenage insurgent detonated a suicide vest.

 

In a review of the nighttime strike for a relative of one of the dead Rangers, military officials sketched out the sequence of events using small dots to chart the soldiers’ movements. Who, the relative asked, was this man — the one represented by a blue dot and nearly killed by the suicide bomber?

 

After some hesi­ta­tion, the military briefers answered with three letters: FBI.

The FBI’s transformation from a crime-fighting agency to a counterterrorism organization in the wake of the Sept. 11, 2001, attacks has been well documented. Less widely known has been the bureau’s role in secret operations against al-Qaeda and its affiliates in Iraq and Afghanistan, among other locations around the world.