It becomes obvious to assume that Powers has not read "The Financing of Terror" by James Adams. Powers writes an excellent introduction and description of terrorism. He even astutely brings out that the key to terrorism is money. From here on he rapidly goes downhill and ends on a note of the ridiculous.
Unlike Adams, he does not bring out the apparent deduction which calls for the curtailment of terrorism by reducing the means by which it can flourish.
Personnel, planning, airline tickets, team training, hotel rooms, safe houses, communications, arms, rockets, explosives, electronic devices of all kinds, rental cars, and other types of transportation are just a partial list of what expenses can be for one terrorist excursion which may easily run up to $1 million or more.
It becomes clear cut that making war on terrorism would not be as effective as taking definite steps to come down hard on those who are doing the financing.