Wars are expensive. The recruitment and sustainment of fighters in the field, the ongoing purchases of weapons and munitions, as well as the myriad other costs of struggle, add up.
So why isn’t the United States going after Islamic State’s funding sources as a way of lessening or eliminating their strength at making war? Follow the money back, cut it off, and you strike a blow much more devastating than an airstrike. But that has not happened. Why?