What justice do the families of terrorists deserve? Deuteronomy 24:16

Terrorism has been part and parcel of the political discourse of nations all over the world since 9/11.  The evil on display in terrorist acts has caused great anger, and rightly so, and some of that anger has been aimed not at those committing the terrorist acts themselves (or even supporting them) but at those associated with terrorists by either their ethnicity, country of origin, or religion.  It is easy for a people feeling threatened and afraid to lash out at whichever target they can get their hands upon, including the families of terrorists.  It has even been suggested by an American presidential candidate that we should kill the families of terrorists as a purposeful tactic in violation of the Geneva Convention.
What does God have to say about such guilt by association?  We needn't wonder as to the answer, because God included a denial of the concept of guilt by association in the Law of Moses.  Deuteronomy 24:16 states, "Fathers shall not be put to death for their children, nor children put to death for their fathers; each is to die for his own sin."  To kill the wife or child of a terrorist in retaliation for even a barbarous act of terrorism, is an affront to the justice of God, it is not the action of a people who live according to the ethics of the Word of God.
We've been down this road before, the same guilt by association was used during WWII to justify the leveling of cities from the air, a tactic which was as immoral as it was ineffective.  At the time, it was argued that the civilian population was supporting the war effort through their work in the factories and thus they were fair game, it was a Faustian bargain, and a losing one.
Terrorism seeks to change the attitudes and thought processes of those it is used against.  If we lower our belief in the value of life, justifying it in the name of protecting our own lives and way of life, we will have failed the test.  The Law of God was clear on this issue in the Covenant of Moses, right and wrong hasn't changed.