The Kerry-Abdullah secret deal
On September 11, US Secretary of State Kerry met Saudi King Abdullah at his palace on the Red Sea. The King invited former head of Saudi intelligence, Prince Bandar to attend. There a deal was hammered out which saw Saudi support for the Syrian airstrikes against ISIS on condition Washington backed the Saudis in toppling Assad, a firm ally of Russia and de facto of Iran and an obstacle to Saudi and UAE plans to control the emerging EU natural gas market and destroy Russia's lucrative EU trade. A report in the Wall Street Journal noted there had been "months of behind-the-scenes work by the US and Arab leaders, who agreed on the need to cooperate against Islamic State, but not how or when. The process gave the Saudis leverage to extract a fresh US commitment to beef up training for rebels fighting Mr. Assad, whose demise the Saudis still see as a top priority." 
For the Saudis the war is between two competing age-old vectors of Islam. Saudi Arabia, home to the sacred cities of Mecca and Medina, claims de facto supremacy in the Islamic world of Sunni Islam. The Saudi Sunni form is ultra-conservative Wahhabism, named for an 18th Century Bedouin Islamic fundamentalist or Salafist named Muhammad ibn Abd al-Wahha. The Taliban derive from Wahhabism with the aid of Saudi-financed religious instruction. The Gulf Emirates and Kuwait also adhere to the Sunni Wahhabism of the Saudis, as does the Emir of Qatar. Iran on the other hand historically is the heart of the smaller branch of Islam, the Shi'ite. Iraq's population is some 61% majority Shi'ite. Syria's President, Bashar al-Assad is a member of a satellite of the Shi'ite branch known as Alawite. Some 23% of Turkey is also Alawite Muslim. To complicate the picture more, across a bridge from Saudi Arabia sits the tiny island country, Bahrain where as many as 75% of the population is Shi'ite but the ruling Al-Khalifa family is Sunni and firmly tied to Saudi Arabia. Moreover, the richest Saudi oil region is dominated by Shi'ite Muslims who work the oil installations of Ras Tanura.
Now if we map the resources of known natural gas reserves in the entire Persian Gulf region, the motives of the Saudi-led Qatar and UAE in financing with billions of dollars the opposition to Assad, including the Sunni ISIS, becomes clearer. Natural gas has become the favored "clean energy" source for the 21st Century and the EU is the world's largest growth market for gas, a major reason Washington wants to break the Gazprom-EU supply dependency to weaken Russia and keep control over the EU via loyal proxies like Qatar.
The world's largest known natural gas reservoir sits in the middle of the Persian Gulf straddling part in the territorial waters of Qatar and part in Iran. The Iranian part is called North Pars. In 2006 China's state-owned CNOOC signed an agreement with Iran to develop North Pars and build LNG infrastructure to bring the gas to China.
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Then you wonder why Europe should take in the refugees. They are benefiting from the destruction of the refugees homelands for access to natural resources.