VP Joe Biden just got in trouble (again) for telling the truth (again). The Saudis and other US "allies" in the region are funding the extremists. Osama bin Laden was a Saudi. Al Qaeda is a Saudi creation. Until we deal with that, we are just going to keep pushing the terrorists into different countries to recruit more of the unemployed, disaffected and easily swayed.
But we will never get to source of their power, which is money as much as ideology.