A war monitor said Tuesday that Israel had "destroyed the most important military sites in Syria" with a flurry of air strikes since the fall of president Bashar al-Assad's government.

Israel, which borders Syria, sent troops into a buffer zone on the east of the Israeli-annexed Golan Heights after Assad's fall, in what Foreign Minister Gideon Saar described as a "limited and temporary step" for "security reasons".

It has also carried out "about 250 air strikes on Syrian territory" over the last 48 hours with the aim of destroying the former regime's military capabilities, according to the Syrian Observatory for Human Rights. 

"Israel destroyed the most important military sites in Syria, including Syrian airports and their warehouses, aircraft squadrons, radars, military signal stations, and many weapons and ammunition depots in various locations in most Syrian governorates," the Britain-based Observatory said in a statement Tuesday. 

Near the port city of Latakia, Israel targeted an air defense facility and damaged Syrian naval ships as well as military warehouses. 

In and around the capital Damascus, strikes targeted military installations, research centers, and the electronic warfare administration. 

Early Tuesday, AFP journalists heard loud explosions in Damascus, hours after the strikes reported by the Observatory.