Follow the bucks. Recruiting, training, equipping, paying and deploying a fighting force with all the support necessary costs a fortune. The Saudis are financing these “Islamists” Post bin Laden al Queda is a Saudi financed Sunni international fighting force. They are deployed in Syria and Iraq fighting to create an Arabic speaking Sunni confederation composed of large parts of Syria and Iraq to confront Iran.
Congratulations, the duck comes down and gives you $50.
The points you left out in your prescient response are:
(A) The Saudis have deep hooks into the political class of both parties. George W Bush's democracy experiment in Iraq was at least in part influenced by the Saudis fear of a Shia led veiled dictatorship. Individuals who had direct influence on the POTUS included Jim Baker and other Houston influence peddlers and fixers who the Saudis had helped make very wealthy men.
(B) The Mahdi and Brennan are philo-Sunni Muslims who along with their Saudi friends thought disrupting Alawi ruled Syria and encouraging a ‘Sunni revival’ in Iraq would work well as part of the ‘Arab Spring’ to contain Iran and insulate the Saudis who are the official ‘Guardians of the Holy Cities of Islam’. The ISIS may be blowback or it may be a covertly controlled Saudi (or some faction of the Saudi establishment such as the Bin Turki clan) only time will tell.
What is clear is the US faces the possibility of either having to launch a huge NEO operation that would be as big as a large military operation or having hundreds of US nationals murdered and hundreds more held hostage.