In Damascus, a dramatic couple of days have culminated in a radical UN-brokered deal that could tip the scales in the war for the Syrian capital and in the death of Zahran Alloush, Syria's best known rebel leader. But while the war in Damascus grabs all the headlines, incremental changes continue to reshape the political landscape in the north, where a complex four-sided war rages between the self-proclaimed Islamic State, a powerful Kurdish militia, President Bashar al-Assad’s central government, and a variety of Sunni Arab rebels backed by Turkey, Saudi Arabia, and the United States.

We recently published a long piece on Syria in Crisis about the U.S.-backed and Kurdish-dominated Syrian Democratic Forces (SDF) and its struggle against the Islamic State extremists. The SDF’s offensive on al-Houl, a small town near the Iraqi border, met with success on November 13 and has since enabled further progress in the area south of Hasakah, a provincial capital close to Syria’s main oil-producing region. Having previously taken Kobane and Tal Abyad, north of the Islamic State headquarters in Raqqa in central Syria, and areas around Hasakah and on the Iraqi border in the east, the Kurds are steadily downgrading jihadi defenses in northern Syria.

In fact, the Islamic State is now under severe pressure from pretty much every direction. It is battling rival Sunni Arab rebels north of Aleppo and trying to contain Assad's forces east of Aleppo and east of Homs, near Palmyra. Meanwhile, in Iraq, it has just lost the city of Sinjar to the Kurdish Peshmerga forces and now stands poised to lose Ramadi to the Iraqi army.

Small wonder that the audio message released on December 26 by the group’s self-proclaimed caliph, Abu Bakr al-Baghdadi, struck a defensive tone, even more than his spokesperson Abu Mohammed al-Adnani did last June. Putting on a brave face and insisting that victory is surely around the corner, Baghdadi reminded Islamic State loyalists that they had seen worse in the past and that God has promised them paradise regardless of whether they win or lose.

Taking the October Dam

In my Syria in Crisis text on the SDF, I noted that there has been a lot of talk about an SDF offensive toward Raqqa, not necessarily intended to seize the city but to overburden Islamic State defenses, but I also wrote that this “seems to remain a work in progress.”

Now, finally, that military campaign seems to have begun. On December 23, the SDF announced the beginning of a new offensive south of Kobane. It had hardly started before the Kurds reached and seized their primary goal, the October (or Tishrin) Dam on the Euphrates, which fell to the SDF on December 26. Unless we’ve witnessed a tactical retreat or a diversion of some kind, the Islamic State appears to have been too badly overstretched to put up a real fight.

If so, that’s a real sign of weakness. The October Dam is a nice catch for the Kurds and an equally big loss for the Islamic State. It is a major infrastructural asset, as one of northern Syria’s most important power stations, responsible for two-fifths of Syria’s hydroelectric power. It is second only to the Soviet-built Revolution Dam, or Sadd al-Thawra, which is located further downstream on the other end of Lake Assad, an artificial body of water created by the dam itself.

What is perhaps less obvious is that the Kurds have also just captured the last remaining western passage over the Euphrates outside the immediate vicinity of Raqqa. Before the war, there were a total of four places you could cross the river before it swells out to become Lake Assad (which goes all the way down to the Revolution Dam, followed by the Baath Dam, followed by Raqqa itself). These four places were:

  1. An old wooden bridge in the Syrian-Turkish border town of Jarabulous, which remains under Islamic State control on the Western shore.
  2. The newer Shiyoukh Bridge just south of Jarabulous.
  3. The modern bridge at Qarah Qawzaq, which is located some thirty or forty kilometers to the south of Jarabulous, depending on which side of the river you’re driving on. This is where the main M4 highway between Hasakah and Aleppo crosses the Euphrates.
  4. The October Dam, which can also function as a bridge.

Three of these have been destroyed. The Jarabulous Bridge was bombed by the Syrian government in 2012. The Shiyoukh Bridge was blown up by the Islamic State when it lost Kobane this spring, to prevent the Kurds from pursuing its fighters into the eastern Aleppo countryside. The same fate befell the Qarah Qawzaq Bridge in March, when the Kurds continued south from Kobane.

Recent strategic victories by the Kurds over the self-proclaimed Islamic State have bolstered prospects for continued Kurdish expansion.

That leaves the October Dam as the sole remaining link between the Kurdish-controlled Kobane region and the Islamic State strongholds in al-Bab and Manbij east of Aleppo. Now it is in Kurdish hands, apparently undamaged.

Prospects for Continued Kurdish Expansion

Since retaking the Kobane enclave and linking it through Tal Abyad to their towns in the east, such as Amoude, Qamishli, and Malikiya, the Syrian Kurds have dreamt of creating a fully contiguous territory along the Turkish border. The outlying Efrin enclave remains isolated and exposed, tucked in among hostile Arab and Turkish regions northwest of Aleppo. But reaching Efrin would require the Kurds to go west across the Euphrates, take Jarabulous, fight their way first through the Islamic State and then through the Sunni rebels in the strategically crucial Aazaz Corridor.

It seems impossible already, and that's before we take a major political obstacle into account: the Kurds' key ally, the United States, has promised Turkey to refrain from backing any Kurdish offensives west of the Euphrates. That's because the driving force behind the SDF is the Kurdistan Workers’ Party, or PKK, which has its origins among Kurds in Turkey and is still fighting the government in Ankara. Instead, the Americans are most likely coaxing the SDF to keep going south into Arab territory near Raqqa in order to force the Islamic State to pull troops home from the Aleppo front.

Then again, every step west would empower the Kurdish groups politically and put pressure on their enemies, all of whom fear a Kurdish expansion into the Aleppo region. It would also unnerve Turkey, which is a goal in and of itself for the PKK. And opening a front across the river from the October Dam also makes great military sense in the war against the Islamic State. The jihadi group is currently battling on two fronts in Aleppo, against Turkish- and American- backed Sunni Islamist rebels near Marea, and the pro-Assad Tiger Forces of the Syrian Arab Army, near the Kweiris Airport. If SDF units step across the river and start moving on Manbij, or even seek to link up with Assad’s forces in Kweiris, the Islamic State’s forces in Aleppo will be trapped in a three front war. If jihadi lines collapse under this pressure, territory could shift hands very quickly—and when time comes to divide the spoils, can the Kurds afford to be absent from the table?