High-level officials, diplomats, ministers and top military brass kicked off three days of talks at the Munich Security Conference Friday amid a US warning to Iran over stalled nuclear talks.
US Vice President Joe Biden, who is due to attend the Munich talks on Saturday, began a three-nation European tour cautioning Iran that the opportunity for talks with the West over Tehran's contested nuclear programme was not open-ended.
A day after meeting Chancellor Angela Merkel in Berlin, freshly-inaugurated Biden is due to address participants in Munich on Saturday and turn his attentions 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 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 acknowledgment 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.
Brahimi and al-Khatib take part in late-night talks on Syria in Munich Friday.
NATO's plan to withdraw the bulk of its 100,000 combat troops from Afghanistan by the end of 2014 as well as developments in the Muslim and Arab world two years after the Arab Spring revolts are also set to be themes here.
German Finance Minister Wolfgang Schaeuble and Spanish Foreign Minister Jose Manuel Garcia-Margallo join a discussion on the euro crisis and the EU's future later Friday, when energy issues are also a focus.
Opening the conference, German Defence Minister Thomas de Maiziere said he was optimistic that the US and Europe could rely on each other and must be able to do so even as both regions turn towards Asia.
"For the US, Europe may not be the best conceivable partner in the world, but it is without any doubt the best possible partner," he said.
Iranian Foreign Minister Ali Akbar Salehi is expected to attend the Munich talks as well as EU foreign policy chief Catherine Ashton, who represents the so-called P5+1 group of the United States, China, Russia, Britain, France and Germany in talks on Iran's nuclear ambitions.
"President (Barack) Obama has made clear that containment is not an option. We will prevent Iran from getting a nuclear weapon," Germany's Sueddeutsche Zeitung daily quoted Biden as saying.
"We think there is time and space for diplomacy -- accompanied with economic pressure. But this window will not be open for an unlimited time," he said in remarks published in German.
"We are continuing with the P5+1 group to work for a diplomatic solution and we have said from the beginning that we are prepared to hold a bilateral meeting," Biden, who also attended the Munich conference in 2009, said.
Iran and the six world powers held three rounds of talks last year aimed at easing the standoff over Iran's nuclear activities, which Tehran insists are entirely peaceful, but the last round ended in stalemate in June in Moscow.
Another round of talks was initially expected to be held in December or January but a date and a location have still not been set amid indications that neither side is prepared to change substantially its position.
Mali, where France launched an offensive on January 11 as Islamists who had ruled the country's north for months advanced south towards the capital Bamako, is also set to focus minds in Munich.