Israel played down weekend air strikes reported to have killed dozens of Syrian soldiers close to Damascus, saying they were not aimed at influencing its neighbor's civil war but only at stopping Iranian missiles reaching Lebanese Hezbollah militants.
Oil prices spiked above $105 a barrel, their highest in nearly a month, on Monday as the air strikes on Friday and Sunday prompted fears of a wider spillover of the two-year old conflict in Syria that could affect Middle East oil exports.
"There are no winds of war," Yair Golan, the general commanding Israeli forces on the Syrian and Lebanese fronts, told reporters while out jogging with troops.
"Do you see tension? There is no tension. Do I look tense to you?" he said, according to the Maariv NRG news website.
Israel's Prime Minister Benjamin Netanyahu came under veiled criticism in Beijing, where he began a scheduled visit in an apparent sign of confidence Syrian President Bashar al-Assad would not retaliate. China urged restraint without mentioning Israel by name.
Russia, Assad's other protector on the U.N. Security Council, said the strikes by Israel "caused particular alarm". President Vladimir Putin and U.S. Secretary of State John Kerry will meet on Tuesday to try to tackle differences over the Syrian crisis.
Israeli officials said the raids were not connected with Syria's civil war but aimed at stopping Hezbollah, an ally of Iran, acquiring weapons to strike Israeli territory.
Israel aimed to avoid "an increase in tension with Syria by making clear that if there is activity, it is only against Hezbollah, not against the Syrian regime" Veteran lawmaker Tzachi Hanegbi, a confidant of Netanyahu, told Israel Radio.
The Syrian Observatory for Human Rights, an opposition monitoring group based in Britain, said at least 42 Syrian soldiers were killed in the strikes and 100 others were missing.
Other opposition sources put the death toll at 300 soldiers, mostly belonging to the elite Republican Guards, a praetorian unit that forms the last line of defense of Damascus and is comprised mainly of members of Assad's Alawite sect, an offshoot of Shi'ite Islam that has controlled Syria since the 1960s.
As well as the heavily-fortified Hamah compound, linked to Syria's chemical and biological weapons program, the warplanes hit military facilities manned by Republican Guards on Qasioun Mountain overlooking Damascus and the nearby Barada River basin.
Residents, activists and rebel sources said the area is a supply route to the Lebanese Shi'ite militant group Hezbollah, but missiles for Hezbollah did not appear to be the only target.
Air defenses comprising Russian made surface-to-air missiles and anti-aircraft guns on Qasioun and overlooking the rebellious Damascus district of Barzeh were also hit, they said. Their statements could not be verified due to restrictions on media.
"The destruction appeared to be massive," said one activist in Damascus, who did not want to be identified.
Russia said it was concerned the chances of foreign military intervention in Syria were growing, suggesting its worry stemmed in part from reports about the alleged use of chemical weapons in the conflict that has killed 70,000 people.
"The further escalation of armed confrontation sharply increases the risk of creating new areas of tension, in addition to Syria, in Lebanon, and the destabilization of the so-far relatively calm atmosphere on the Lebanese-Israeli border," Russian Foreign Ministry spokesman Alexander Lukashevich said.
Assad's government accused Israel of effectively helping al Qaeda Islamist "terrorists" and said the strikes "open the door to all possibilities". It said many civilians had died but there was no official casualty toll.
Israeli officials said that, as after a similar attack in the same area in January, they were calculating Assad would not fight a well-armed neighbor while preoccupied with survival against a revolt that grew from pro-democracy protests in 2011.
Israel has not confirmed the latest attacks officially, but has reinforced anti-missile batteries in the north. It said two rockets landed, by mistake, on Monday, in the Golan Heights, the Israeli-occupied area near Syria's border with Israel.
"They were fired erroneously as a byproduct of internal conflict in Syria," an Israeli military spokesman said.
Syria would be no match for Israel in any direct military showdown. But Damascus, with its leverage over Lebanon's Hezbollah, could consider proxy attacks through Lebanon.
Tehran, which has long backed Assad, whose Alawite minority has religious ties to Iran's Shi'ite Islam, denied Israel's attack was on arms for Hezbollah. Hezbollah did not comment.
Moscow and Beijing have blocked Western-backed measures against Assad at the United Nations Security Council, opposing any proposal that has his exit from power as a starting point.
Allegations of the use of chemical weapons - long described by Western leaders as a "red line" that would have serious consequences - have added to regional and international tension.
After months of increasingly bitter fighting, Assad's government and the rebels have each accused the other of carrying out three chemical weapon attacks.
Syria is not part of the international treaty that bans poison gas but has said it would never use it in an internal conflict. Rebels say they have no access to chemical arms.
The White House has said the Syrian government has probably used chemical weapons. A U.S. official said on Monday Washington had no information to suggest that rebels had used them.
A U.N. inquiry commission said on Monday war crimes investigators had reached no conclusions on whether any side in the Syrian war has used chemical weapons, after a suggestion from one of the team that rebel forces had done so.