BEIRUT/JERUSALEM, Jan 21 (Reuters) -
Israel struck in Syria early on Monday as part of its increasingly open assault on Iran's presence there, shaking the night sky over Damascus with an hour of loud explosions in a second consecutive night of military action.
The threat of open confrontation between arch-enemies Israel and Iran has long simmered in Syria, as the Iranian military has established a presence there since early in its civil war in support of President Bashar al-Assad against rebels
Israel, regarding Iran as its biggest threat, has repeatedly attacked Iranian targets and those of allied militia, including Lebanon's Hezbollah, in Syria, aiming to push them far from its frontier.
The Israeli military said its fighter jets had attacked the Iranian targets early on Monday, including munition stores, a position in the Damascus International Airport, an intelligence site and a military training camp.
Israeli jets then targeted Syrian defense batteries after coming under fire, the Israeli military said, and the Defense Ministry of Russia, Assad's strongest ally, said four Syrian soldiers were killed and six wounded.
The Syrian Observatory for Human Rights, a Britain-based war monitor, said 11 people had been killed.
Syrian air defenses, supplied by Russia, had destroyed more than 30 cruise missiles and guided bombs, the Russian Defense Ministry said, according to RIA news agency.
Syrian state media, citing a military source, said the country had endured "intense attack through consecutive waves of guided missiles, but had destroyed most "hostile targets".
Israel's target was the Iranian Quds Force, a special unit in charge of the Islamic Revolutionary Guards Corps overseas operations, the Israeli military said.
It followed a previous night of cross-border fire, which Israel said was prompted by a rocket fired at a packed ski resort in the Golan Heights, close to the frontier with Syria.
Israel did not say who it suspected of carrying out the rocket attack.
Syria said it was Israel that had attacked, and its own air defenses that had repelled the assault.
Israeli Prime Minister Benjamin Netanyahu, who is hoping to win a fifth term in an April 9 election, has been playing up military sorties into Syria that Israel had previously preferred to keep quiet.
"We have a permanent policy, to strike at the Iranian entrenchment in Syria and hurt whoever tries to hurt us," he said on Sunday.
Israel, which appointed a new military chief last week, also appeared keen to signal zero tolerance for Sunday's rocket launch, which it said had been foiled by its Iron Dome interceptor system.
The Israeli army said the Mount Hermon ski resort in the Israeli-controlled Golan Heights would be shut for the day. It added that otherwise things remained "routine" along the frontier with Syria.
Netanyahu last week acknowledged an Israeli attack on what he called an Iranian arms cache in Syria, where Tehran provides Damascus with vital support.
He told his cabinet Israel had carried out "hundreds" of attacks over the past years of Syria's war to curtail Iran and its ally Hezbollah.
Iran has said it has no plans to quit Syria, where it has helped Assad fight off an eight-year rebellion against his rule. Most of the country is now back under Damascus' control, and Assad's alliances with both Iran and Russia remain very strong.
Last summer, he took back rebel-held territory in southwest Syria, near the Golan Heights, in a campaign that was supported by Iran-backed militias.