ISTANBUL — Extremists of the Islamic State on Monday seized nearly all of Deir el Zour, the last town not under their control in eastern Syria, after executing the emir of a rival jihadi group, the Nusra Front, anti-government activists reported.
The takeover of the city in the heart of Syria’s oil and gas producing zone marked a major advance for the Islamic Front, which now controls a large swath of territory in eastern Syria and more than one-third of Iraq.
The military airport remains in the hands of the Syrian government along with some parts of the city, but for all intents and purposes, eastern Syria is now under the control of a militia the United States views as terrorists.
The Islamic State posted a picture of the dead Nusra emir, Safwan al Hint, on the Internet. Activists said he was killed as he tried to flee Deir el Zour for the nearby town of Hatla. According to one account, when Islamic State guards spotted him, he attempted to kill himself and them by detonating an explosive belt he was wearing, but they opened fire first and he was unable to trigger the explosion.
Anti-government activists on the Deir el Zour Local Coordinating Committee said on their Facebook page that fighters for al Qaida-affiliated Nusra and the Islamist group Ahrar al Sham had evacuated their bases on Sunday night, suggesting that they were able to escape the city as part of a deal with the Islamic State.
Fighters for the pro-Western Free Syrian Army seized large parts of Deir el Zour from the Syrian government in May 2012 and turned over some of the control to allied groups such as Nusra, in part because the FSA did not have enough weapons for its fighters.
Until earlier this year, Nusra and the Free Syrian Army considered the Islamic State an ally against the government of Syrian President Bashar Assad. But Nusra and the FSA turned on the Islamic State over that group’s harsh interpretation of Islam and its brutal rule in the parts of Syria it controlled.
Nusra, the Free Syrian Army and groups affiliated with a third rebel coalition, the Islamic Front, forced the Islamic State fighters from much of western Syria. The group, however, held on to its stronghold in Raqqa province. Early this month, flush with U.S. weapons it captured when it seized Iraqi military bases in June, the Islamic State captured the Syrian border town of Abu Kamal and advanced through five other towns without resistance.
Now the biggest question is the response of the Assad government, which until earlier this month was rarely in conflict with the fighters of the Islamic State. As the group expanded its control in Iraq, however, Syrian government aircraft bombed an Islamic State convoy and positions along the Iraqi border.
Anti-government activists said many basic services had improved after the Islamic State took control of the city, including electricity, water and food supplies, and that there had been no arrests or field executions Monday.