The Islamic State has taken control of several towns in eastern Syria, further securing its line of communications along the Euphrates River Valley from Western Anbar in Iraq to the city of Raqqah in Syria. Over the past two days, some local tribes and rebel factions in the area have responded to the pressure by pledging allegiance to the Islamic State, while other groups have vowed to continue fighting its advance.
Today, the Islamic State took full control of the city of Mayadan and the town of Shuhail in Deir al Zour province after the Al Nusrah Front, al Qaeda's official branch in Syria, withdrew from the towns without a fight. Parts of Mayadin, the largest city between the provincial capital city of Deir al Zour and the border town of Albu Kamal, have been under the control of the Islamic State since the end of June.
Shuhail is the home town of Abu Muhammad al Julani, the emir of the Al Nusrah Front. During the Iraqi insurgency from 2004-2011, the town served as a jumpoff point for jihadists fighting for al Qaeda in Iraq and its successor organization, the Islamic State of Iraq, to launch attacks across the border. Once the Syrian Civil War began in 2011, Shuhail became a hub for the activities of the Al Nusrah Front inside Syria.
Additionally, the Al Omar oil field, which is located just east of Mayadan, has been under the control of the Islamic State since the end of June. The oil field is estimated to output 10,000 barrels of oil a day, and will serve as additional income for the group, which seized more than $400 million from banks when it took control of Mosul on June 10.
The Islamic State's consolidation of control over most of Deir al Zour province has forced more defections from jihadist groups. The tribes in Shuhail as well as in the villages of Hariji and Namliyah, along with insurgent groups Jaish al Islam, Jaish Mouta al Islami, Liwa al Ikhlas, and Harakat Taliban al Islamiya, have pledged bayat, or an oath of loyalty, to Abu Bakr al Baghdadi, the self-proclaimed leader of the Islamic State who calls himself Caliph Ibrahim. A video of the announcement was released on YouTube.
But in the town of Ashara and nearby villages, units from the Al Nusrah Front, Ahrar al Sham (an Islamist brigade closely allied with the Al Nusrah Front), and Free Syrian Army pledged to continue to fight the Islamic State.
The Islamic State now controls contiguous territory along the Euphrates River Valley from the town of Jarabulus, which borders Turkey, in Syria's northern Aleppo province to the town of Anah in Iraq's Anbar province. The city of Haditha, farther south of Anah, is contested, while the Haditha Dam is under government control. Ramadi is also contested, but Fallujah and several nearby cities and towns are under the control of the Islamic State.
The Islamic State's recent advances in Deir al Zour were enabled by the takeover of the town of Albu Kamal on June 25 as well as Al Qaim in Iraq. An Egyptian Al Nusrah Front leader from Albu Kamal defected to to the Islamic State, causing the town to fall.
Control of the Euphrates River Valley along both sides of the Iraq-Syria border reinforces the Islamic State's perception that it has destroyed the boundaries between the two countries and is truly restoring the caliphate. Militarily, the Islamic State is now able to freely move fighters between Iraq and Syria to reinforce areas in need as well as expand on its recent gains in both countries.