Forgive me if this should be in the Israel/Hamas thread, but I find this somewhat applicable due to the extremist groups out there and the respective countries that fund them.
http://www.reuters.com/article/2014/...0FJ2M820140714
The link above is an article regarding an $11 billion arms sale from the U.S. to Qatar. Meanwhile, Qatar is known to actively fund Hamas and provide safe refuge for key Hamas leaders. On the other hand, the U.S. is obviously a huge ally of Israel. The U.S. isn't going to turn away an arms sale of this magnitude.
It strikes me how intertwined and convoluted foreign relations are between countries and the extremist groups they back. I'm sure if one digs deep enough, the same can be said for whoever is funding ISIS.