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The US and its Kurdish militia allies in eastern Syria, the centre of the country's oil production, have come under increased pressure over the past week, with the wounding of several American personnel in two drone attacks, and Arab tribal proxies of Tehran challenging the grip of Kurdish auxiliaries in the area.
A western diplomat, speaking to The National, said the latest violence was a confluence of threats to the US and allies amid wider regional clashes, which could serve Syria's ambition to regain control of the east.
The violence – which has included pitched battles between militias backed by Damascus and US-backed Kurdish groups, comes as Israel and the US await an Iranian response to the killing of Hamas leader Ismail Haniyeh in Tehran.
It is expected to include a second direct attack on Israel by Iran or a spike in attacks on Israel by Iran's proxy militias in the region. Some of those militias, already clashing with US forces, could also step up attacks against American outposts.
Increased attacks in recent days against US bases in Syria and Iraq are seen as shot across the bows of Washington, which had sent sizeable reinforcements to the Middle East to help defend Israel.
The western diplomat said that “Iran is raising the pressure dose” on the US in eastern Syria, which is divided between Iranian, Russian and Kurdish-US zones of control.
“We could be seeing the beginning of a low-intensity, Iranian-backed resistance movement against the US and the Kurds,” he said.
Tehran, he said, does not want high-intensity operations to a degree that could draw US retaliation, against its troops, or against the Syrian Army, which has taken some offensive positions along the Euphrates River, particularly in Deir Ezzor, but has not launched any operations.
Instead, Damascus and Tehran rely in the area on a mix of regionally recruited militias, including Iraqis trained and funded by Iran, as well as Syrian paramilitary groups. In the past, such forces have even included units of Afghan and Pakistani Shiites.
Whatever Iran's strategy, violence is rising.
A Kurdish official in the YPG-controlled administration in the area told The National that a Kurdish security force, Asayish, launched late on Saturday a pre-emptive operation in the Hasakah countryside to stay a step ahead of Iran-linked fighters.
The official said that Iran had managed to form an Arab tribal force in Deir Ezzor whose members were previously divided between allegiance to the SDF and hostility towards it.
“It is an Iranian push with Arab faces,” he said. “The Iranians are sending a message to the US that they can widen their circle of response in Syria.”
The official said that the SDF has retaliated by surrounding Syrian security bases in the centre of Hasakah and Qamishli over the last several days and cutting off water from the compounds. The tension eased last night, he said, after Russian mediation.
US under attack
A US official told Reuters that several US personnel and others from allied countries were wounded in Friday's drone attack at Rumalyn Landing Zone, near one of Syria's largest oilfields.
Eastern Syria is the main link in a supply route from Tehran to Hezbollah in Lebanon. The US presence in the area, about 900 troops, has complicated this effort and acted as a check on Iran's regional efforts, as well as on Turkey, which had captured territory from the Kurdish militia over the last eight years.
But Ankara had stopped short of advancing into the heartland of eastern Syria, where the major oilfields are along with the bulk of Syria's wheat production.
Syrian President Bashar Al Assad has said the Kurdish-US occupation of the oilfields is a vital reason behind the country's economic woes, although outside experts point to the government's mismanagement of its economy and western sanctions.
Iraqi groups re-join fray
The US military initially indicated that there were no casualties in Friday's drone attack. It came after a rocket strike on Monday that wounded five US personnel at Al Asad airbase in western Iraq, later claimed by an Iran-linked Iraqi militia.
US Defence Secretary Lloyd Austin has said the US would not tolerate attacks on American personnel but Washington was also trying to de-escalate tensions in the region.
The US has less than 1,000 troops in Syria co-located with the Syrian Democratic Forces, a proxy force set up by the US at the beginning of the fight against ISIS in 2015, to act as a ground component in the American-led battles.
The SDF is dominated by the Peoples Protection Units (YPG) a Syrian Kurdish militia of the Turkish Kurdistan Workers Party (PKK) designated as a terrorist group in the US, much of Europe, and in Turkey.
The US intervention in the Syrian civil led to a Kurdish takeover of vast swathes of eastern Syria, a mixed region of Kurds and Arab tribes, raising resentment and helping Iran build allies in the area.
Last week, Arab tribal groups supported by the Syrian military and Iran attacked SDF areas in the eastern Deir Ezzor governorate. Several civilians were killed in the fighting, and hundreds fled their homes as two small towns on the Euphrates exchanged hands.
The tribal forces are led by a pro-Iranian militia called Lions of Okaidat. Like many pro-Iranian paramilitary groups, it was set up by Iran's Islamic Revolutionary Guard Corps, three years ago.
The force includes disgruntled fighters from other tribes who participated in a failed uprising last year against the SDF militia, which is dominated by Kurdish fighters.
The challenge to Kurdish militia domination has raised tensions between with Syrian Army.
For decades, the two sides have had an understanding of dividing the administration in the main urban centres of the east between them, particularly the cities Hasakah and Qamishli, where the Syrian Army and intelligence had kept main bases in the city centres.
Those agreements were mostly broken, or at best strained, as the country descended into civil war in 2011.
