At least 18 pro-Iranian soldiers have been killed in air strikes at militant allies in eastern Syria, war watchdogs say.
Syrian Human Rights Watch (SOHR) said it is still unknown who was responsible for the attack in the Al Bukamal city near the Iraqi border.
A British-based watchdog with extensive ties across Syria says 18 soldiers have been killed, but their nationality has not been identified.
Al Bukamal is a city in the Deir ez-Zur region that comprises the largest desert area in eastern Syria, dominated by Daesh militants.
The area is dominated by two separatist groups and the Kurds supported by the United States while the Damascus regime is supported by Iran and Russia.
According to the watchdog group, in June 2018, attacks near the Iraqi border killed 55 pro-regime soldiers, most of them Syrians and Iraqis.
An American official confirmed that Israel was responsible for the attack but the Jewish state refused to comment.
Israel has carried out hundreds of attacks in Syria targeting the positions of Lebanese Shiite movements, Hezbollah and Iranian forces, who have vowed to prevent control of Syria’s territory.