Factions loyal to Tehran of multiple nationalities on the one hand, and the US-backed Syrian Democratic Forces, on the other hand, share control of the Deir ez-Zor governorate in eastern Syria , where Washington launched strikes Thursday night.

The region witnesses from time to time tensions and bombing, the latest of which was the strikes carried out by the Americans in response to the bombing of one of their bases in Al-Hasakah Governorate, which claimed the life of an American contractor. The strikes targeted groups that Washington said were affiliated with the Iranian Revolutionary Guard, killing 11 of its members, according to the Syrian Observatory for Human Rights on Friday.
What are the forces deployed in the province of Deir Ezzor, through which the Euphrates River passes?

The Syrian regime forces control the western bank of the Euphrates River, which is the most important area of influence for Iran and its loyal groups in Syria.

The Observatory estimates that there are about 15,000 fighters from Iraqi, Afghan and Pakistani groups loyal to Iran in Deir ez-Zor, specifically the area extending between the border cities of Al-Bukamal with Iraq and Deir ez-Zor, passing through Al-Mayadeen.

The pro-regime groups are:
The Iranian Revolutionary Guard: Thousands of fighters and military advisors from the Revolutionary Guard are deployed in Syria, but Tehran only talks about advisers who assist the government forces.

In August, Iranian official media announced the killing of a high-ranking officer in the Iranian Revolutionary Guards during a "mission as a military advisor" he was performing in Syria, without giving details.

Iraqi factions: Iraqi groups are fighting alongside the Syrian government forces at Iranian request. Today, they are mainly deployed on the border strip between Iraq and Syria, since the end of operations against the Islamic State in Iraq and then Syria. They are based in the city of Al-Bukamal.

Among the most prominent of these groups: "Hezbollah Brigades", whose spokesman says that its fighters are deployed in Syria as "advisers" to protect the Iraqi borders.

These battalions are the most prominent factions of the Iraqi Popular Mobilization Forces. Analysts consider it the third force in the axis led by Tehran in the region, after the Revolutionary Guards and the Lebanese Hezbollah.

Also among the Iraqi factions are the “Ka’ib Sayyid al-Shuhada,” the “Imam Ali Brigades,” and the “Hezbollah al-Nujaba Movement.”

- Lebanese Hezbollah: The party that has been fighting on the side of the Syrian regime openly since 2013, especially leaders in the Deir ez-Zor region. The number of its forces in Syria has decreased over the past two years with the decline in the intensity of the battles and the restoration of control over about two-thirds of the country by the regime forces.

- The Afghan "Fatemiyoun" Brigade and the Pakistani "Zainabiyoun" Brigade: The Iranian Revolutionary Guard established the two brigades from Afghan and Pakistani Shiite fighters. They participated in several battles in Syria, and today they maintain important sites in Deir ez-Zor, as well as other Syrian regions.

The Fatemiyoun Brigade, according to the Syrian Observatory, is one of the largest pro-Iranian factions in Syria.

Since 2019, Washington has imposed sanctions on the two factions.

In addition to foreign groups, the Iranians have established local groups in Deir ez-Zor, to which thousands of Syrian fighters now belong, who receive an attractive financial allowance.

The Syrian Democratic Forces, led by the US-backed Kurdish People's Protection Units, are stationed on the eastern bank of the Euphrates.

The Syrian Democratic Forces were able to control the entire area with the support of the international coalition to combat the jihadists led by Washington, following fierce battles with the Islamic State, the last of which took place in 2019 in the last stronghold of the organization in Syria in the border village of Al-Baghouz.

The Kurdish self-administration administers the region through local councils.

The international coalition forces, most notably the US forces, are deployed in the region, and are located at a base in the Al-Omar oil field, or what has become known as the "Green Zone", in addition to the Koniko gas field.

American forces are deployed in other bases in Syria in the province of Hasakah (northeast) and Raqqa (north), in addition to the al-Tanf base in the south, which was established in 2016, and is located near the Jordanian and Iraqi borders, and enjoys strategic importance as it is located on the Baghdad-Damascus road.

The most important Syrian oil fields are located in Deir Ezzor Governorate, and are controlled by the Syrian Democratic Forces, the most important of which is the Al-Omar oil field, which is the largest in the country, in addition to the Al-Tanak and Jafra fields. It also controls the Coneco gas field.

On the western side, there are oil fields controlled by the regime forces, including the fields of Al-Ward, Al-Taym, Al-Shoula and Al-Nishan.
This border area is an important route for the Iraqi Brigades and the Lebanese Hezbollah, as well as other pro-Iranian groups, for the transfer of weapons and fighters. It is also used to transport goods of all kinds between Iraq and Syria.

Over the years, trucks carrying weapons, ammunition, warehouses, and military sites belonging to these groups have been subjected to air strikes, especially in the area between Al-Mayadeen and Al-Bukamal. Some of them were adopted by the American forces, and others were attributed to Israel, which always affirms its determination to prevent "Iranian entrenchment" in Syria.