BEIRUT/WASHINGTON: An ISIS suicide bomber detonated a tank at the Syrian military airport outside the city of Deir al-Zor, one of the last remaining government strongholds in the east of the country, jihadi social media and a monitoring group said Friday.

One ISIS Twitter account published two photographs of a smiling man it named Abu al-Farouq al-Libi, who it said carried out the “suicide operation.”

The Al-Qaeda offshoot ISIS has been gradually consolidating control of the oil-producing Deir al-Zor region this year. President Bashar Assad’s forces have held on to the local military air base and parts of the provincial capital.

On Dec. 6, militants entered the base but were swiftly repelled. Syria’s state news agency SANA said the army had pursued ISIS fighters in the area around Deir al-Zor base and killed many of them.

The Britain-based Syrian Observatory for Human Rights said the tank blew up on the outskirts of the base but gave no details of casualties or other damage. After the blast, clashes raged for several hours, killing at least nine ISIS militants. Of the casualties one was a Tunisian and another from Morocco, it said.

The Observatory said that after the battle, regime forces were able to retrieve three of the enemy corpses – they were placed on a truck, which then drove around areas of Deir al-Zor under regime control.

The practice has been reported on a few occasions during the latest ISIS offensive to take the airport, while local, anti-regime activists have said some of the corpses were decapitated, to match the punishments that ISIS has often meted out to its enemies.

Rami Abdel-Rahman, head of the Observatory, said that ISIS militants, who this week were driven off by regime fire, once again appeared to be inching closer to the base.

However, he said that ISIS also appeared to be fighting a morale problem. Abdel-Rahman said the Al-Qaeda splinter group was replacing its fighters in the border town of Ain al-Arab in Aleppo province with new ones, to avoid negative fallout from the casualties that they have suffered in their siege, which began in September.

Three ISIS fighters were killed in skirmishes with Kurdish militia in and around Ain al-Arab, the Observatory said.

Also, the United States and its allies carried out 27 airstrikes on ISIS targets in Syria and Iraq in the past three days, according to U.S. military officials.

Fighting positions, buildings and fortifications were hit in seven attacks near Ain al-Arab and Aleppo and on the border with Iraq, according to a statement from the Combined Joint Task Force for the coalition overseeing the operation.

ISIS was hit with 20 strikes in Iraq near the cities of Ramadi, Al-Rutbah, Mosul, Al-Qaim, Samarra, Rawah and Al-Asad, the statement said.

The Syrian air force also pounded ISIS positions in and around Deir al-Zor, but the strikes, late Thursday, ended up mortally wounding two civilians in the village of Hatleh, the Observatory said.

Meanwhile, in the city of Al-Bab in Aleppo province, ISIS militants executed a Syrian man they said was responsible for the deaths of nearly 200 people.

The man was decapitated after Friday prayers and his body displayed in public, the Observatory said.

It said, citing local activists, that ISIS found the man guilty of turning over people to the regime, and marking territory “where Muslims gather” so that it could be bombed or targeted by regime forces.

The activists said ISIS accused him of causing the deaths of 196 people and the wounding of more than 700 others, while receiving payments from the regime.