<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by pynchonesque:
Shooting down a passenger plane would end the political career of the President authorizing it, which may become a goal in itself for some nations/groups.</font>
Don't count on that ending the political career of the President. The POTUS has already been insulated from such an eventuality and the political fallout. The order to shoot down a passenger airliner need not be made by a cabinet level member or the Pres or VP. This has been explicitly discussed and mentioned by a variety of government officials and certain high-ranking military officers are "ok'd" to give such an ok.