At least 15 Iranian backed militiamen were killed in an air raid in Eastern Syria near the border with Iraq on Tuesday according to the U.K. based Syrian Observatory for Human Rights.
The raid the Imam Ali base near Al-Sekka and Al Bokamal in the area of Deir Ezzor hitting military potions and weapons warehouses.
The attack was attributed to Israel, though Turkey was also known to operate in the area and had launched airstrikes against militants.
American Fox News last week reported that Iran is building an underground advanced weapons storage in the area.
New satellite images from Image Sat International (ISI) from May 12, show bulldozers at the entrance to the structure, which is estimated to be around 15 feet wide. ISI assessed that the tunnel can fit vehicles carrying advanced weapons systems.
The Israeli military said earlier that it had attacked Syrian military positions in Southern Syria.
The attack came after an armed group of militants attempted to attack an explosive device near the border fence to target Israeli troops.
Israel has said it considers the Syrian regime responsible for acts of aggression originating inside Syria.