A Kurdish militia supported by the US has made territorial gains against Arab mutineers in eastern Syria, but a militarised Arab tribal backlash is growing in the area, sources on both sides have said.
The ethnic fighting is undermining a US-supervised order in the east, the centre of Syria's oil output and its main wheat farming region.
More than 120 people have been reported killed in fighting in the past two weeks after members of the People Protection Units militia, known as the YPG, arrested an Arab warlord who goes by the name Abu Khawla.
A source in the Kurdish-controlled administration in eastern Syria said YPG infantry units have in the past two days regained that area of Buseira, the home region of Abu Khalwa, in Deir Ezzor governorate.
“The tribes withdrew because they lack the heavy weapons for fixed warfare. But the YPG has left itself open to guerrilla attacks,” the source said.
“The Kurds have no organic base in Deir Ezzor. It will be up to the Americans to renegotiate an accommodation,” the source says, referring the overwhelmingly Arab governorate.
Arab tribes had surrounded a YPG outpost in Buseira, which is situated between the Euphrates River and Al Khabour, a largely dry tributary. Arab auxiliaries have also launched attacks on YPG forces in the governorate of Aleppo, the easternmost frontier of the YPG zone in Syria.
Although Abu Khawla worked with the YPG in a US-supervised coalition against ISIS, he has lately been contesting YPG control of the war economy in the east.
His loyalists have erected their own roadblocks to collect taxes and moved to remove YPG installed tribal leaders.
The US embassy in Syria, which has no physical presence in the country, said US officials had met Kurdish commanders and “community leaders” to discuss de-escalation in the east.
Although Abu Khawla was not seen as a popular commander, his arrest has been regarded as an affront to Arabs who resent the US-supported Kurdish expansion.
Alliances between the YPG and Arab tribes, which Washington has been trying to solidly for years, mainly though the lure of money have started to unravel.
Over the past few weeks, tribal leaders have issued calls to unite to expel the YPG from Deir Ezzor, the weakest link in the wide strip of territory it controls, because of the lack of indigenous Kurds in the areas.
The military heft of the YPG is centred in the neighbouring governorate of Hasakah, where the Kurds constitute a majority of the population.
Ibrhim Al Hafl, a senior member of the Okeidat tribe which has turned against the YPG, said he was willing to work on restoring peace to the east, as long as the US meets a list of demands to end “systematic practices” against Arabs.
He said only Arab figures should be in charge of Deir Ezzor, with a direct channel to US forces, dispensing with the need to go through the YPG.
Security and services in the area must be resorted, he said, adding that the YPG has unjustly arrested members of Bukair tribe, to which Abu Khawla belongs, and that they should all be released.
Up to the fighting last month, the YPG controlled, with US backing, large swathes of territory along the border with Turkey, stretching from the east of the Euphrates river to the border with Iraq. These areas include parts of the Aleppo, Deir Ezzor and Aleppo governorates.
The Kurdish militias have emerged as among the most pragmatic players in the Syrian civil war, which started after the security forces of President Bashar Al Assad used force to suppress the 2011 revolt against his rule.
The Kurdish Union Democratic Party, a forerunner of the YPG, helped the Syrian authorities crush the protest movement but allied with the US in the ensuing civil war.
The YPG has also kept channels open with Damascus and with Russia, which has helped the YPG carve an enclave in the rural area of Tel Rifaat, near the metropolis of Aleppo.
At the weekend, Arab tribes in Aleppo governorate launched attacks against YPG controlled villages in eastern Aleppo, to relieve pressure on the Deir Ezzor Arabs.
The Arab auxiliaries have been slowly advancing in the area of Minbig, near the Euphrates, reports said.