The size of that force is still being discussed . NEW : The Taliban claimed responsibility for the attack . NATO says four NATO coalition service members have been killed . NATO did not release the names of those killed . A Pentagon official says the attack happened at Bagram Air Base .
NEW : The Taliban claimed responsibility for the attack . NATO says four NATO coalition service members have been killed . NATO did not release the names of those killed . A Pentagon official says the attack happened at Bagram Air Base .