I'm also feeling a bit apocalyptic; seems that everything is happening at once, very rapidly. It's Muslim Mayhem time.
BTW, this may be naive, since I don't know anything about military or prison security, but why weren't these men incarcerated in a totally foreign country where they would not know the language or customs & stick out like a sore thumb? It's much easier to capture prisoners in such a situation. Instead, in Yemen they will simply fade into the woodwork among a Muslim, and sympathetic, populace.
In earlier times of law, a prison warden who let his prisoner escape would undergo the fate of the prisoner in his place.