The Free Syrian Army (FSA), the “moderate” armed opposition in the country, receives a lot of attention. But two of the most successful factions fighting Assad’s forces are Islamist extremist groups: Jabhat al-Nusra and the Islamic State of Iraq and Syria (ISIS), the latter of which is now amassing territory in Iraq and threatening to further destabilize the entire region. And that success is in part due to the support they have received from two Persian Gulf countries: Qatar and Saudi Arabia.

Qatar’s military and economic largesse has made its way to Jabhat al-Nusra, to the point that a senior Qatari official told me he can identify al-Nusra commanders by the blocks they control in various Syrian cities. But ISIS is another matter. As one senior Qatari official stated, “ISIS has been a Saudi project.”

ISIS, in fact, may have been a major part of Bandar’s covert-ops strategy in Syria. The Saudi government, for its part, has denied allegations, including claims made by Iraqi Prime Minister Nouri al-Maliki, that it has directly supported ISIS. But there are also signs that the kingdom recently shifted its assistance—whether direct or indirect—away from extremist factions in Syria and toward more moderate opposition groups.

The United States, France, and Turkey have long sought to support the weak and disorganized FSA, and to secure commitments from Qatar and Saudi Arabia to do the same. When Mohammed bin Nayef took the Syrian file from Bandar in February, the Saudi government appeared to finally be endorsing this strategy. As The Washington Post’s David Ignatius wrote at the time, “Prince Mohammed’s new oversight role reflects the increasing concern in Saudi Arabia and other neighboring countries about al-Qaeda’s growing power within the Syrian opposition.”

The worry at the time, punctuated by a February meeting between U.S. National Security Adviser Susan Rice and the intelligence chiefs of Turkey, Qatar, Jordan, and others in the region, was that ISIS and al-Qaeda-affiliated Jabhat al-Nusra had emerged as the preeminent rebel forces in Syria. The governments who took part reportedly committed to cut off ISIS and Jabhat al-Nusra, and support the FSA instead. But while official support from Qatar and Saudi Arabia appears to have dried up, non-governmental military and financial support may still be flowing from these countries to Islamist groups.

Senior White House officials have refused to discuss the question of any particular Saudi officials aiding ISIS and have not commented on Bandar’s departure. But they have emphasized that Saudi Arabia is now both supporting moderate Syrian rebels and helping coordinate regional policies to deal with an ascendant ISIS threat.

Like elements of the mujahideen, which benefited from U.S. financial and military support during the Soviet war in Afghanistan and then later turned on the West in the form of al-Qaeda, ISIS achieved scale and consequence through Saudi support, only to now pose a grave threat to the kingdom and the region. It’s this concern about blowback that has motivated Joint Chiefs of Staff Chairman Martin Dempsey and Defense Secretary Chuck Hagel to encourage restraint in arming Syrian rebels. President Obama has so far heeded these warnings.

John McCain’s desire to help rebel forces toss off a brutal dictator and fight for a more just and inclusive Syria is admirable. But as has been proven repeatedly in the Middle East, ousting strongmen doesn’t necessarily produce more favorable successor governments. Embracing figures like Bandar, who may have tried to achieve his objectives in Syria by building a monster, isn't worth it.

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