U.S. Vice President Joe Biden held talks with German Chancellor Angela Merkel in Berlin on February 1, at the start of a tour of Europe.
Ahead of their talks, Biden called for Iran to return to negotiations over its nuclear program in an interview with the German "Sueddeutsche Zeitung" newspaper.
Biden repeated U.S. offers of direct talks, but warned Tehran the diplomatic window would not remain open indefinitely.
Biden is also due to attend an annual security conference in Munich, where the Syrian crisis is expected to dominate and where Biden is expected to meet with Syrian top opposition leader Moaz al-Khatib, international peace envoy for Syria Lakhdar Brahimi, and Russian Foreign Minister Sergei Lavrov.
Biden's talks on Syria come as concerns mount following an Israeli attack within its borders.
Based on reporting by dpa and AFP