The Syrian Kurds have capitalized on a Russian backed Syrian operation in northern Aleppo. Battlefied gains have upended Turkey's Syria policy and increased the risk of a larger conflagaration.
Syrian Kurdish forces under the cover of Russian airstrikes continue to advance in the northern Aleppo countryside, creating facts on the ground in the five-year Syrian conflict that are sounding alarm bells in Ankara.
The steady offensive of Syrian Kurdish YPG fighters and allied Arab and Turkmen Free Syrian Army groups collectively fighting under the banner of the Syrian Democratic Forces (SDF) comes as Turkish and Saudi Arabian-backed Islamist rebel factions collapse under a barrage of Russian airstrikes.
Four months of Russian airstrikes have shifted the balance of power in the war in favor of the Syrian army. Regime and allied forces have virtually encircled rebel-held parts of Aleppo and cut off the northern supply line running to the Turkish border.
Turkey considers the YPG, the armed wing of the PYD, which is the Syrian affiliate of the PKK, as a terrorist group on par with the "Islamic State." The PKK has been fighting a three decade war against the Turkish state in the name of greater Kurdish rights and autonomy.
The SDF blitz sets up Kurdish dominated forces for taking Azaz, a strategic political and logistical hub for Turkish backed rebels fighting both the Assad regime and IS. Advancing several kilometers to the east would put the YPG up against territory controlled by IS.
"The collapse of the Azaz area would mean the end for a Turkish backed project in north Aleppo countryside -- the Marea Operations Room, which was backed in order to clear north Aleppo countryside of IS," Aymenn al-Tamimi, a Syria analyst at the Middle East Forum, told DW.
Turkey has responded to the Kurdish drive by lobbing artillery across the border at SDF positions, even as the United States and France, among others, called on their NATO ally to show restraint.
"We will not allow Azaz to fall," Turkish Prime Minister Ahmet Davutoglu said on Monday.
Washington, Ankara and the Kurds
Turkish PM Ahmet Davutoglu has accused the Kurds of being "Russia's legion working as mercenaries" to harm Turkey.
Complicating the picture is heightened tension between Washington and Ankara. The United States views the YPG as the best fighting force against IS and the SDF as an integral part of the strategy to push the Sunni terror group back in to remote northeastern Syria. The ultimate objective is to use the SDF to oust IS from its self-declared capital of Raqqa.
Turkey has looked on with concern as the Syrian Kurds over the course of the conflict have carved out autonomous regions and expanded territory in largely Kurdish populated areas referred to by Kurds as Rojava. Turkey fears the knock-on effect the Kurdish experiment in self-government could have on its own restive Kurdish population.
Much to the annoyance of Turkey, the US has backed the YPG since it pushed back an IS assault on Kobane in late 2014. Since then, Syrian Kurds have rapidly expanded areas under their control with the backing of US air power.
Turkish President Recep Tayyip Erdogan has blasted the cozy relationship between the US and Syrian Kurds, saying that Washington must choose between the YPG and Turkey. The United States recognizes the PKK as a terrorist organization but not the PYD/YPG.
"In the end, the US will have to choose between Turkey and the PKK. It will be a difficult choice, but if they need to choose, Turkey will be its option," Mensur Akgun, the director of the Global Political Trends Center, a foreign policy think tank in Istanbul, told DW.
What move next?
The YPG's ultimate objective is to unite the cantons of Afrin and Kobane, creating a contiguous Kurdish entity along the border with Turkey. For Turkey, this is a so-called "red line" that has being repeatedly tested, most recently in northern Aleppo, and previously when the SDF expanded beyond the Tishreen dam.
In response to developments in northern Aleppo, Ankara is mulling sending in ground troops with Saudi Arabia and the United Arab Emirates, ostensibly to go after IS. However, Turkish officials have said any such operation would need the backing of the West, notably the United States.
The United States has rebuffed repeated Turkish proposals to form a no-fly zone or safe-zone for rebels and refugees. While Ankara may be concerned about IS and refugees, it is more focused on the Kurds, raising questions over the country's intentions in Western capitals.
Further complicating things is the escalating political and military brinksmanship between Ankara and Moscow following Turkey's downing of a Russian jet in November. Russia has responded by playing the proverbial Kurdish card, backing the PYD politically in UN-backed peace talks and last week allowing the party to open an office in Moscow.
This complex picture leaves Ankara in a position of not being able to act unilaterally in Syria against the YPG/PYD while having the Syrian Kurds backed by its ally the United States and its foe Russia.
In this context, the danger is that a desperate Turkey may miscalculate or pursue policies with unintended consequences. The smattering of towns and olive groves in Aleppo's hinterland are a complex battleground that could trigger a larger conflagration, as Turkey and Russia continue to up the ante.