Israel on Sunday implicitly confirmed it staged an air strike on Syria last week as President Bashar al-Assad accused the Jewish state of trying to further destabilise his war-torn country.
The foreign minister of Damascus ally Iran, meanwhile, said he welcomed Syrian opposition leader Ahmed Moaz al-Khatib's stated readiness to hold talks with representatives of Assad's regime.
Four days after an air raid which Damascus said targeted a military complex near the capital, Israeli Defence Minister Ehud Barak spoke to reporters in Munich but refrained from explicitly confirming that Israel staged the strike.
Barak told the Munich Security Conference that it was "another proof that when we say something we mean it."
"We say that we don't think that it should be allowable to bring advanced weapon systems into Lebanon, the Hezbollah from Syria, when Assad falls," Barak said.
Wednesday's air strike targeted surface-to-air missiles and an adjacent military complex believed to house chemical agents, according to a US official, who spoke on condition of anonymity.
Damascus has threatened to retaliate, further fuelling fears of a regional spillover of the country's 22-month conflict which the UN says has already left more than 60,000 people dead.
Turkish Foreign Minister Ahmet Davutoglu, quoted in Hurriyet newspaper, mocked Syria for its failure to retaliate against its longtime arch-foe.
"Why hasn't the Syrian army, which has attacked its own innocent people with planes, tanks and shells for 22 months, respond to this Israeli operation?" he asked "Why doesn't it throw even a pebble?"
In the wake of the strike, US Defence Secretary Leon Panetta told AFP that Washington was increasingly concerned that Syria's "chaos" could allow Lebanon's powerful Hezbollah movement to obtain sophisticated weapons from Damascus.
Israeli armed forces chief Lieutenant General Benny Gantz on Sunday started a visit to Washington with the Syrian conflict and Iran's controversial nuclear programme on his agenda.
In Damascus, Assad accused Israel of seeking to "destabilise" Syria, state news agency SANA reported.
The raid "unmasked the true role Israel is playing, in collaboration with foreign enemy forces and their agents on Syrian soil," he told Saeed Jalili, who heads Iran's Supreme National Security Council.
key Damascus and Hezbollah backer Tehran also said on Sunday that it welcomed opposition chief Khatib's overture for talks with regime representatives.
"It's a good step forward," Foreign Minister Ali Akbar Salehi said at the Munich Security Conference, where he said he had held a "very good meeting" with Khatib.
Iran has joined UN Security Council members Russia and China in consistently backing Assad's regime throughout the almost two year-long conflict which has also forced more than 700,000 people to flee Syria.
After Khatib met Iranian and Russian representatives in Munich, opposition spokesman Walid al-Bunni told AFP by telephone that Moscow must now pressure Assad to end the spiralling conflict.
"The ball is now in Russia's court," the Syrian National Coalition's Bunni said, although he conceded that there has been "no breakthrough in Russia's stance."
Syria's state-owned daily Ath Thawra also said there has been no shift in Moscow's stance.
Russia has blocked three UN Security Council resolutions threatening sanctions against Assad over the crackdown in Syria.
On the ground, at least 15 people, including five children and a woman, were killed in a missile attack by the army on Sunday on a rebel-held area of the northern city of Aleppo, according to the Syrian Observatory for Human Rights.
The Britain-based watchdog, which relies on a network of activists and medics, warned that the number of casualties could rise as people scrambled to sift through the rubble of a collapsed five-storey building in the Ansari district.
Video distributed by activists showed a man describing the carnage. "I saw a 13-year-old's body sprawled on the ground, I saw mutilated body parts everywhere," he told the amateur cameraman.