Israeli warplanes struck areas in and around the Syrian capital Sunday, setting off a series of explosions as they targeted a shipment of highly accurate, Iranian-made guided missiles believed to be bound for Lebanon's Hezbollah militant group, officials and activists said.

The attack, the second in three days and the third this year, signaled a sharp escalation of Israel's involvement in Syria's bloody civil war. Syrian state media reported that Israeli missiles struck a military and scientific research center near Damascus and caused casualties.

Syria's government called the attacks against against its territory a "flagrant violation of international law" that has made the Middle East "more dangerous" and warned it has the right "to defend its people by all available means."