Freshly re-inaugurated US Vice President Joe Biden, who on Friday met Chancellor Angela Merkel in Berlin, traveled to Munich, where he will turn his attention to Syria amid fears the conflict may spill over the country's borders.
He is scheduled to meet Russian Foreign Minister Sergei Lavrov and Syrian opposition chief Moaz al-Khatib, and also see UN-Arab League envoy to Syria Lakhdar Brahimi in the southern German city, the White House said.
Outgoing US Secretary of State Hillary Clinton said Iran is stepping up its support for the Syrian regime and that Russia is still arming it, heightening concerns after Damascus threatened to retaliate over a reported Israeli air raid.
"What we would like to see from other countries, including Russia, is an acknowledgement that (Syrian President) Bashar al-Assad must go and that there needs to be a transition within Syria to a new government," said Ben Rhodes, a White House national security adviser.
Khatib on Friday said the international community must not be a "bystander" to the "tragedy" of the Syrian people and reiterated his willingness to talk to the regime.
He joined UN-Arab League envoy Brahimi for late-night panel talks at the Munich Security Conference on Friday.
"As a gesture of good will... we are ready to sit at the negotiating table with the regime but we don't want their hands to be full of blood," Khatib said calling for the release of detainees.
In a surprise move Wednesday, Khatib announced he was ready for dialogue with officials of President Bashar al-Assad's regime subject to conditions, including that "160,000 detainees" are released.
But the opposition Syrian National Coalition said on Thursday that any talks on the country's political future must be about the departure of the regime of Assad.
Asked what Khatib would ask of the US and other governments, he said, speaking through an interpreter, "everything you would provide us with to end the injustice is acceptable".
"The Syrian people are living a tragedy right now," he added.
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He called for "some kind of electronic interference" to prevent the aircraft of the regime shelling the Syrian people.
"If that doesn't work I would demand to destroy the planes and weapons of the Syrian regime because it is just not acceptable for the international community to be a bystander just watching what's happening to the Syrian people," he said.
"We hate war, we do not advocate war... I am warning if this crisis persists it would have grave ramifications on the whole region," he added.