The Syrian Observatory for Human Rights (SOHR) reported a number of ISIS sudden attacks on posts of Iranian-backed militias and regime forces in the surrounding areas of Arak oil field in east Homs desert.
The attack was followed by clashes between the two sides, amid reports of casualties.
ISIS cells targeted a guard post of al-Qura Guards, militias backed by Iranian Revolutionary Guard Corps (IRGC), on the bank of Euphrates river in al-Asharah city in the eastern countryside of Deir Ezzor, killing four Syrian militiamen and injuring others.
Earlier, a bomb planted by unknown gunmen believed to be of ISIS cells, exploded in the car carrying militiamen, near Wadha village of Maskanah town in the eastern countryside of Aleppo, according to the Observatory.
As a result, four Iranian-backed militiamen were killed, and two others injured.
ISIS also killed eight regime-backed militiamen in surprise attacks on their posts and checkpoints in different areas in the Syrian desert. In response, Russian jets executed tens of airstrikes on ISIS positions, leaving casualties.
Since March 2019, SOHR documented various ISIS attacks, bombings, and ambushes which resulted in the deaths of at least 1,339 regime soldiers and loyalists of various nationalities, including two Russians, and 145 Iranian-backed militiamen of non-Syrian nationalities.
Also, four civilians working in gas fields, 11 shepherds, and four other people were killed in ISIS attacks during the same period, according to the war monitor.
About 754 ISIS members were also killed in exchanged attacks and bombardment since March 2019.