Seven European military observers have landed in Berlin, after pro-Russian separatists in eastern Ukraine released them from captivity.
The Organization for Security and Cooperation in Europe (OSCE) observer team landed in Berlin on the evening on May 3.
German Defense Minister Ursula von der Leyen said she was "filled with great relief" that the men had "landed here safe and well."
The seven observers and five Ukrainian military officers had been held by pro-Russian separatists near the flashpoint city of Slovyansk since April 25.
They were released early on May 3 following intervention from a Kremlin envoy, Vladimir Lukin.
Meanwhile, on May 3, acting Ukrainian President Oleksandr Turchynov announced a period of mourning for more than 40 people killed -- mostly pro-Russia separatists -- in fighting in Odesa on May 2.
The street clashes in the Black Sea port city ended with a blaze at a trade union building, apparently after firebombs were thrown inside.
Elsewhere, Ukraine's Interior Ministry says its forces have retaken the headquarters of the security services in the city of Kramatorsk as an offensive against pro-Russia separatists in the east continues.
The ministry said on May 3 that its forces had also regained control of the city's airport and a television tower and controlled all checkpoints around the city.
Local television showed pictures of armored personnel carriers moving through the town.
Kramatorsk is south of the rebel stronghold of Slovyansk, which the Interior Ministry said has also now been surrounded by its troops.
In the eastern city of Donetsk, a couple of hundred pro-Russia protesters stormed the governor's business premises and the state security headquarters, ransacking files, and smashing windows.
U.S. Secretary of State John Kerry spoke to Russian Foreign Minister Sergei Lavrov by telephone about the crisis in Ukraine.
Both sides said they agreed that the OSCE should play a bigger role in helping to reduce tension.
Based on reporting by AFP and Reuters