By Peter Bergen and David Sterman
Editor's note: Peter Bergen is CNN's national security analyst and a director at the New America Foundation. David Sterman is a graduate student at Georgetown University's National Security Studies Program.
(CNN) - Sometime in late 2007, Basaaly Saeed Moalin, a cabdriver living in San Diego, began to have a series of phone conversations with Aden Hashi Ayrow, one of the leaders of Al-Shabaab, a notorious Somali terrorist group.
Moalin had no idea the National Security Agency was listening in.
In one of those phone calls Ayrow urged Moalin to send money to Al-Shabaab, telling him that he urgently needed several thousand dollars.
At one point Ayrow told Moalin that it was "time to finance the jihad" and at another, "You are running late with the stuff. Send some and something will happen."