Bomb the convoy out of existence. Mercilessness is the only way to end ISIS and to send the message to would-be recruits worldwide that no matter what vile tactic they dream up, it will fail and they will die in very short order. Any form of mercy no matter how small is instantly exploited and taken advantage of for maximum gain. If you allow this human-shield tactic to work, they will just start doing it more often and the problem will get worse.