US Vice President Joe Biden will discuss the carnage in Syria in meetings on Saturday with Russian Foreign Minister Sergei Lavrov and Syrian opposition chief Moaz al-Khatib, the White House said.
Biden will hold the meetings, and also see UN-Arab League envoy to Syria Lakhdar Brahimi at the Munich Security Conference on a trip that will also include talks with leaders of Germany, France and Britain.
His initiative on Syria comes as fears mount that the sectarian war could spill over into other countries and after an Israeli raid on targets inside Syria, described by Damascus as a military research center and in some reports as a convoy.
While not confirming the targets of the Israeli air raid, the White House warned on Thursday that Syria's government should not transfer arms to the Lebanon-based Hezbollah militia.
"We've been very clear that Syria should not further destabilize the region by transferring, for instance, weaponry to Hezbollah," said Ben Rhodes, a deputy US national security advisor.
"We also, of course, have been very clear beyond that that we're closely monitoring Syria's chemical weapons as well," he said.
Rhodes, asked about Iranian and Syrian threats to retaliate against Israel, said that such rhetoric from Tehran showed how concerned leaders there were about the prospect of President Bashar al-Assad's regime falling.
Officials said that Biden, in his meetings in Munich, would discuss getting more humanitarian aid into Syria where 60,000 people have now been killed in violence which sparked a refugee crisis.
"What we would like to see from other countries, including Russia, is an acknowledgment that Bashar al-Assad must go and that there needs to be a transition within Syria to a new government," said Rhodes.
Washington has denounced Russia's opposition to UN Security Council efforts to reach a global consensus on the need for Assad to leave.
The Obama administration has resisted calls for it to deploy military assets to help opposition forces in Syria, and has stopped short of arming forces fighting Assad's troops.
But it has provided non-lethal logistics, and medical and humanitarian support to rebels.
President Barack Obama this week announced $155 million in new aid to Syria, taking the overall contribution of humanitarian supplies to $365 million.
Biden's trip will take him to Germany, France and Britain.
He arrives in Berlin on Friday and hold talks with Chancellor Angela Merkel, before heading to Munich, where he will deliver a speech to the conference on Saturday and hold his bilateral meetings.
On Monday, Biden will see French President Francois Hollande, before leaving for London, where he will meet British Prime Minister David Cameron and Deputy Prime Minister Nick Clegg on Tuesday.
As well as security issues, Biden will also engage European leaders on the steps they have taken to stave off the EU's debt crisis and on the need to crank up the pace of economic growth, officials said.