Iran's Revolutionary Guards have admitted that one of their officers was killed in an Israeli airstrike near the Syrian capital, Damascus, on Friday. The Guards vowed to retaliate, but the increasing frequency of Israeli airstrikes on Syria suggests that Israel is determined to confront Iran's strong presence in the country. Friday’s attack was the second strike near Damascus in two days. There was no immediate statement from Israel, which usually declines to comment on reports of strikes in Syria. “The Revolutionary Guards Corps (IRGC) has announced the martyrdom of guardsman Milad Haydari, one of the IRGC's military advisers and officers,” in the Israeli attack, the IRGC said in a statement reported by the official news agency, IRNA. The statement also criticized the international silence regarding “the ongoing violation of the sovereignty and territorial integrity of an independent member state of the UN.” It emphasized that Israel “will undoubtedly receive a response to this crime.” The air strike was the sixth attack by Israel in Syria this month, according to the Syrian Observatory for Human Rights. Israel has for years carried out attacks against what it has described as Iran-linked targets in Syria, where Tehran's influence has grown since it began supporting President Bashar al-Assad in the civil war that began in 2011. Iran says its officers serve in an advisory role in Syria at the invitation of Damascus. Dozens of IRGC members including senior officers have been killed in Syria during the war, according to Reuters. Syrian state media said that Israel had attacked just after midnight, firing missiles that hit a site in the Damascus countryside. Syrian air defenses had shot down several missiles, it said, without mentioning any casualties. The Syrian foreign ministry also condemned Friday’s attack and said Syria stood ready to confront any further attacks. Iranian-backed groups, including Lebanon's heavily armed Hezbollah, and Iraqi paramilitary groups have positions around the capital and in Syria’s north, east and south.