CNN Fareed Zakaria GPS December 20, 2015 18:08:00
The last month, month and a half. we're going at the infrastructure around the oil, around the refineries and that's not the only source isil has. it is sophisticated in terms of its financing and started out by con quering territory and seizing banks and then spending money in the banks. it then moved on to develop an oil revenue stream. we have to make sure we move with isil as a world community to make sure they do not have that kind of access and that means going across border sales and formal and informal and stopping flow of money into isil territory. >> what is the hardest part of this?...