US-backed YPG in northern Syria says it has reached agreements with the n and Iran-backed regime of Bashar al-Assad to allow reinforcements to be sent to , to sustain their war against Turkey.

YPG is regarded by as an extension of the Kurdistan Workers’ Party (PKK), which has fought a three-decade armed conflict in and is regarded as a terrorist group by the US and the European Union.

Kino Gabriel, spokesman for the Kurdish-dominated n Democratic Forces (SDF), said to Reuters news agency that YPG has reached an understanding with the Assad regime.

“There are different ways to get reinforcements to , but the fundamental route is via regime forces. There are understandings between the two forces … for the sake of delivering reinforcements to .”

While YPG depends on Assad to reach , Damascus also needs the YPG’s cooperation to source grain and from areas of the northeast under Kurdish control, the source added.

Pro-Assad forces backed by Russia and Iran, and YPG forces have fought each other elsewhere in , and Damascus opposes YPG demands for autonomy. But, in , they have a common enemy and a mutual interest in blocking Turkish advances.

A commander in the military alliance fighting in support of Assad said, on condition of anonymity, “The n regime is helping the with humanitarian support and some logistics, like turning a blind eye and allowing Kurdish support to reach some fronts.”

, which regards the Kurdish YPG militia in as a terrorist organization and a threat to its southern border, launched an assault on the region last month. In return, YPG has asked Damascus to send forces into the region to fight the Turkish army.

The Assad shows no sign of doing so, but it is providing indirect help by allowing men and supplies to reach through the territory it controls, representatives of both sides told Reuters.

Assad stands to gain while doing little.

The arrival of reinforcements is likely to sustain YPG, bog down the Turkish forces, and prolong a conflict that is sapping the resources of military powers that rival Assad for control of n territory.

For the US, it is a welcomed development in ’s seven-year-old war, as complicated as it may be. Nevertheless, its strategic ally, the YPG, must at times make deals with Assad for its survival.

Turkish campaign moves slowly

The Turkish military is making slow gains nearly three weeks into the operation it calls “Olive Branch”.

The US has relied on the YPG as a vital ground component of its war against the ic State of Iraq and the Levant (ISIL, also known as ISIS) in , and has backed the group in other Kurdish-controlled regions in northern along the border with .

But US forces are not in , so they have been unable to shield from the attack by , its NATO ally.

The YPG, meanwhile, accuse of giving a green light for the Turkish attack by withdrawing observers it deployed in last year.

The war marks another twist in the complicated story of relations between Assad and the n Kurdish groups, spearheaded by the YPG, that have carved out autonomous regions in northern since the war began in 2011.

The YPG controls nearly all of ’s frontier with . But is separated from the bigger Kurdish-controlled region further east by a 100km-wide zone controlled by the Turkish military and its n militia allies.

For much of the war, Damascus and the YPG have avoided confrontation, at times fighting common enemies, including the rebel groups that are now helping attack .

But tensions have mounted in recent months, with Damascus threatening to march into parts of eastern and northern captured by the SDF, with support from the US-led coalition.

Underlining that, pro-Assad forces attacked the SDF in the eastern province of Deir al-Zor, drawing coalition air attacks overnight that killed more than 100 of the attackers, the coalition said.

“The regime has allowed the YPG to bring people into , while attacking it east of Euphrates (River). I think that is indicative of the state of relations right,” said Noah Bonsey, International Crisis Group’s Senior Analyst on .

He added: “There is still a significant gap between the YPG and regime positions on the future of northeastern .”

Fighting for

The main n Kurdish groups remain wedded to their vision of a where they gain autonomy, in a form of federalism, that is at odds with Assad’s determination to control all of .

Each side has allowed the other to maintain footholds in its territory. In YPG-held Qamishli, Assad forces still control the airport. In the Sheikh Maqsoud district of Aleppo, a regime city, YPG forces patrol the streets.

Scores of from Sheikh Maqsoud have gone to to support the fight, Kurdish officials there said. The short journey requires movement through areas held by the or its Iran-backed Shi’ite militia allies.

“Of course people went from Sheikh Maqsoud – in the hundreds – to bear arms and defend ,” said Badran Himo, a YPG official from Sheikh Maqsoud.

“Around 10 of them were martyred,” he told Reuters as YPG forces held a rally to commemorate one of the dead.

Earlier this week, witnesses say, people drove in a convoy of hundreds of cars to , from other YPG-held areas, to support the group.

The n has ignored appeals by YPG authorities to guard the n border at .

“We tried to convince them, via the ns, to at least protect the borders, to take a position, but we did not get a result,” Aldar Khalil, a top YPG politician, told Reuters.

“If they don’t protect the borders, then at least they don’t have the right to block the way for n patriots who are protecting these borders, regardless of other domestic issues.”

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