A Syrian war monitoring group says Israeli attacks on several sites in Syria have killed 23 fighters, including five Syrian soldiers.
Israel says it struck dozens of Iranian targets in Syria overnight in response to a rocket barrage on Israeli positions in the Golan Heights. It was the biggest Israeli strike in Syria since the 1973 war.
The Russian military says Israel fired more than 70 missiles at Iranian facilities in Syria and that Syrian air defences shot down more than half of them.
The Britain-based Syrian Observatory for Human Rights said on Thursday the overnight attacks struck several military posts for Syrian troops and Iranian-backed militias near the capital, Damascus, in central Syria and in southern Syria.
The head of the Observatory, Rami Abdurrahman, said five Syrian soldiers, including two officers, and 18 militia fighters were killed. Abdurrahman said it was not immediately clear if Iranians were among those killed.
He said the toll was likely to rise because some of the wounded were in critical condition.
The Observatory said the strikes targeted suspected locations of the Lebanese Hezbollah group, as well as areas where Iranian advisers are believed to be based.
The Russian Defence Ministry said in a statement that 28 Israeli F-15 and F-16 fighter jets launched about 60 air-to-surface missiles during the two-hour raid early on Thursday.
It said Israel also fired over 10 tactical surface-to-surface missiles and Syrian air defences shot down over half of the more than 70 missiles fired overall.
Russia is a key ally of Syrian President Bashar Assad, and has been waging its own air campaign on his behalf since 2015.
