In the days and weeks ahead President Obama will face an important decision: whether to allow the conflict in Syria to escalate by approving Turkey’s and Saudi Arabia’s direct intervention, or to come to terms with the continued survival and expanding area of control of the government of Bashar al-Assad. Informed commentators note that this may be the most significant foreign policy decision the President will have to make after seven years in office:

With the Russian-backed Syrian army encircling Aleppo, cutting off Turkish supplies to rebels and advancing on the Islamic State’s capital of Raqqa, a panicked Saudi Arabia and Turkey have set up a joint headquarters to direct an invasion of Syria that could lead to a vast escalation of the war. And there’s only one man who could stop them: President Barack Obama.

The stakes are high: a Turkish-Saudi invasion would risk direct confrontation not only between their own ground forces and the Syrian Arab Army (SAA) of the government in Damascus, but also—more significantly—between Russia and NATO, since Turkey is a member of the alliance. The known unknown is whether Washington has the clout to stop its “allies” in Ankara and Riyadh from presenting the U.S. with a fait accompli.

As I noted in this column over four months ago, “Turkey, Saudi Arabia, the Emirates and Oman would be loath to accept the end of their plan to turn Syria into a permanent Sunni Muslim wedge dividing what they see as a putative Shiite-dominated crescent extending from Iran across Iraq and Syria into northern Lebanon.” For all of them, this geopolitical goal is incompatible with with the stated primary U.S. objective of defeating ISIS (Daesh, ISIL etc). With recent battlefield successes of Bashar’s army, facilitated by Russia’s air power, the imminent prospect of their jihadist protégés’ defeat creates tremendous temptation to raise the stakes.

It is noteworthy that Turkey’s autocratic President Erdogan and Prince Mohammad bin Salman—Saudi Arabia’s de facto chief strategist—have both displayed propensity for unilateral action in recent months. The Turks’ recent reduction of the Kurdish town of Cizre, in the east of the country, to rubble has evaded attention of R2P enthusiasts in Washington (unlike the ongoing drama in Aleppo). The Turkish army’s indiscriminate shelling of Syria’s Kurds—who are rare reliable and effective U.S. allies in the fight against the Islamic State on the ground—have prompted both the Department of State and the Pentagon to press Erdogan to immediately stop attacks. (Somewhat incongruously, they simultaneously asked Kurdish fighters not to expand their areas of control, which could only work to the Turks’ and ISIS’ advantage.) According to Fox News,

The U.S. military is working closely with Kurdish forces in northern Syria, where they have delivered some of the most decisive and lasting blows to Islamic State extremists. But Turkey considers the most effective Syrian Kurdish force, known as the YPG, to be terrorists just like the PKK, the Kurdish insurgent separatists classified as a terrorist group by the U.S., Turkey and the European Union.

It is now evident that Turkey is more interested in destroying the Kurds’ fighting ability on both sides of the border (and  in the fulness of time bringing about the downfall of Bashar al-Assad, with American boots on the ground if possible) than in fighting the Islamic State All along ISIS remains Erdogan’s natural ally in the grand-strategic scheme of things. Not for the first time, Erdogan wants to be a Sunni Islamist tail wagging the American dog:

Turkey has provided the U.S. with evidence it says shows that the YPG has smuggled large amounts of firepower, including weapons made in America, to PKK fighters in Turkey, according to officials from both countries.U.S. officials said they have looked into each case and found no evidence that any arms or ammunition it has given directly to Syrian Kurdish forces to fight Islamic State have been smuggled into Turkey to be used against Turkish security forces.

The other nominal U.S. ally in the region, Saudi Arabia, follows a similar calculus. It is extremely unhappy that in the end the U.S. did not go to war against Iran over the latter’s nuclear program. The Saudis now propose to send their mercenaries into Syria, ostensibly to fight the Islamic State, even though their extremely brutal military campaign against the Shiite Houthis in Yemen is not going anywhere, and even though they also see ISIS as a natural ally in the geopolitical equation. In spite of possessing a mega-billion military, they are not capable of successfully fighting a single-front war against a weak opponent to the south. They cannot wage a two-front war that would entail facing battle-hardened foes like the SAA; but they hope and trust that the U.S. will come to their rescue once they enter the Syrian fray.

The most surprising single element in the equation is the resilience of the SAA. Its collapse has been a regular feature of Western media discourse for five years. No Russian air power, no Iranian advisors, and no Hizballah volunteers would have saved it, had there not been the will to fight among the Syrian army’s rank-and-file. Routine Western predictions of its demise have been proven wrong, not only because the minorities (Allawite, Christian, Druze, etc.) are fighting for their survival, but also because many Syrian Sunni Muslims loath the prospect of living under a Sharia-ordered state offered by U.S.-supported “moderates.” These Sunnis are to this day a significant segment of the SAA general staff, officer corps, and its most effective fighting units.

The utopian dream of a fundamentalist Sunni state, connecting oil and gas rich fields of the Arabian desert and the southern shores of the Persian Gulf with the Mediterranean ports in Syria and with southeastern Turkey, is now in tatters. That dream, translated into burning ambition in the minds of the monarchic Arab kleptocrats, is the geopolitical essence of the Syrian tragedy. It would be foolish, as well as criminal, for the Obama Administration to aid and abet its realization in the waning months of a long and in every other respect disastrous presidency.