Where does ISIL’s money come from?

The U.S. Central Intelligence Agency (CIA) estimated the Islamic State of Iraq and Levant’s (ISIL) combatant manpower to be between 20,000 to 31,500 in Iraq and Syria combined, and that was back in September, before the organization had attracted new recruits from all over the world.

Recently, another new generation terrorist organization in Egypt, the Ansar Beit al-Maqdis, which was responsible for killing 33 security personnel in Sinai on Oct. 24, announced on Nov. 10 that it had joined ISIL, adopting the name “the Sinai Province of the Islamic State.”

According to Turkish security sources, one of the key reasons why fighters in the Syrian and Iraqi theater have been attracted to ISIL is money, along with the group’s armed propaganda based on an obscene level of terror, as can be observed in a recent video showing ISIL militants of different nations beheading 12 people (including Syrian army officers and an American aid worker, Peter Kassig). Turkish sources claim that a number of fighters from the West-leaning Free Syrian Army (FSA), the al-Qaeda-affiliated al-Nusra, and other smaller organizations have tended to defect to ISIL for monthly payments varying between $100 to $500, depending on the rank and ability of the recruit.

On Nov. 14, Germany’s Süddeutsche Zeitung published documents captured from Abdul Rahman al-Bilawi during a raid by Iraqi security on June 5, 2014, a few days before the ISIL advance and capture of Mosul. Al-Bilawi was a high-ranking ISIL commander, controlling all war bureaucracy, including expenditures. We can now read that ISIL purchased American M4 assault rifles for $8,200 per piece and (again American) night vision devices for $2,900.

If CIA estimates are right, we are talking about an...