howard shatz studied it back when it was still known as al qaeda in iraq. the richest terrorist organization. howard good to see you, thank you for being with us. this is a very distinct difference between al qaeda and i.s.i.l. i.s.i.l.'s got a ready source of revenue that does not depend as much on a donor network, does not depend on countries that give you money through the back door. they've got a bit of a business going. >> absolutely. they've always been that way. donations have always been a very small part of their total revenue portfolio. right now their revenue portfolio includes oil as you said. and then also extortion and taxation much like a state would do. >> ransom has become a smaller part of there or is it still a major part of their revenue? >> so ransom has always been a nontrivial but small part of it, nothing compared to extortion or taxation, nothing like oil, or taking over banks throughout iraq and syria. >> you estimated that i.s.i.l. produced more than 150 million barrels of oil a day, that's huge. what's the best way to cut into tha