By David Andrew Weinberg, Special to CNN

Editor’s note: David Andrew Weinberg is a Senior Fellow at the Foundation for Defense of Democracies. The views expressed are the writer’s own.

Saudi Arabia and Qatar have been working overtime arming rebel groups in Syria. But events of the last month suggest these American allies have been throwing their lots in with radical, hardline Islamists.

Some observers are bullishly optimistic about the foreign policies of America’s Gulf allies, suggesting Saudi Arabia backs “the least Islamist component of the rebellion” and Qatar’s young new emir is displaying a more “mature” foreign policy that seeks to avoid controversy in places like Syria. However, there is worrying news coming from Syria’s Raqqa Province, now controlled by the al Qaeda affiliate Islamic State of Iraq and the Levant (ISIL). Hateful books described by several different sources as the area’s new academic curriculum, reportedly originate from Saudi Arabia.

Ali al-Ahmed, who directs the Institute for Gulf Affairs in Washington, has conducted previous reviews of official Saudi textbooks. He told me that although the seal from Saudi Arabia’s education ministry has been removed from the books, they otherwise appear identical to the ones he has reviewed. Al-Ahmed said that the two collections being brandished in Raqqa are “toxic,” promoting extremism and the dehumanization of non-Muslims.

But this isn’t the only development that appears to shed light on Saudi and Qatari objectives in Syria.

ISIL has gone on the offensive against certain Syrian rebel groups that are frequently linked to Qatar’s largesse, including Ahfad al-Rasoul and the Farouq Brigades. However, another recipient of Qatar’s support – arguably the strongest militia around Syria’s largest city, Aleppo – appears to prefer to negotiate with ISIL instead of helping other rebels fight it

Perhaps more worrying is what this Qatari-backed group did next. On September 24, one of its leaders in Aleppo issued a declaration with a handful of other militias that called for an Islamic state and rejected the Western-backed Syrian opposition coalition. Its number one signatory was the Nusra Front, al Qaeda’s other main affiliate in Syria. Roughly half the groups that joined in this announcement were Islamist brigades that have reportedly received backing from either Saudi Arabia or Qatar.

A week later, the head of another Islamist group announced the merger of dozens of rebel organizations around Damascus into a massive “Army of Islam.” Both diplomats and rebel fighters indicated that this merger occurred at the conscious direction of Riyadh. The organization’s leader, Zahran Alloush, studied in Saudi Arabia, where his father is a Salafist cleric.

The merger in Damascus contradicts claims that the Kingdom supports only “quietist” Salafis who reject political Islam, since Alloush’s brigade calls for an Islamic state and flies the black jihadist flag instead of a Syrian one. He has insisted this Damascus merger will not push back against ISIL and has openly advocated ethnic cleansing.

Saudi Arabia has suffered blowback for supporting jihadist groups before, most notably when al Qaeda went on a rampage in the Kingdom a decade ago. However, Saudi Arabia and Qatar have other incentives that push them toward promoting Syrian jihadists or at least turning a blind eye.

Riyadh has long promoted the strident, Salafist ideology of Wahhabi Islam at home and abroad (indeed, the textbooks in question are tagged “distributed free of charge”). Since the Arab Spring, Saudi Arabia has aggressively fanned sectarian hatreds to keep its own disaffected Sunnis and Shiites from joining forces to demand greater rights.

Qatar, noted for its “hyperactive” foreign policy, is so eager to acquire clients in the region that it has shown little concern for these groups’ intensely Islamist principles. Qatar reportedly tried to give the Muslim Brotherhood a stranglehold over Syria’s political opposition and was chastised by the U.S. for letting advanced weapons reach the Nusra Front.

Under pressure this past May, Qatar let Saudi Arabia take charge of the opposition cause in Syria. However, now that Saudi Arabia finds itself in a position of leadership over the rebellion, it also has incentives to encourage a broad military coalition against the al-Assad regime. Evidently, the Saudis have been giving in to that temptation, building a very large but also very jihadist tent among the rebels.

But at what cost? Before the war, Salafists in Syria were not indigenously grounded. Since then, they have opportunistically used this conflict to expand their influence, tapping into material support and sectarian rhetoric from the Gulf.

Some outside observers believe hardliners like Alloush are now the only game in town amongst Syria’s armed opposition. However, the continued expansion of such hardline rebel groups means that enticing Western support for the opposition is going to get much tougher as time goes on.

Yet these developments may be a sign that Saudi Arabia and the rebels are writing off the chances of U.S. military intervention altogether. Washington’s recent decision not to launch missile strikes on Syria infuriated the Saudis, and our exclusive focus on chemical weapons has given the Assad regime a new lease on life.

America’s Gulf allies want al-Assad out, and they want it now. Combined with Qatar and Saudi Arabia’s natural ideological predispositions, this intense desire to win Syria’s civil war seems to be overpowering any possible instincts for caution from the Gulf. Riyadh and Doha are feeding an unruly jihadist problem in Syria that will no doubt create all kinds of headaches for America and the region down the line.