The U.S. now believes five of the 60 Syrian rebels it trained and equipped have been captured by al Nusra in recent days and one rebel was killed, according to a senior defense official.
This happened since the Friday attack on their compound, but U.S. officials declined to say exactly when.
The U.S. is now developing plans to help the rebel force reposition to safer locations because they have come under constant attack by al Nusra, the al Qaeda affiliate in Syria.