Russia unleashed a barrage of missiles, drones and bombs across Ukraine early Saturday, killing five people in a major attack that the mayor of Kharkiv, Ukraine's second largest city, described as unprecedented.

Russia peace negotiations got underway in Turkey on Monday in an effort to find a way forward in ending more than three years of war triggered by Russia's full-scale invasion of its neighbor.

Russia has proposed holding the next round of direct talks with Ukraine in Istanbul on June 2 with a view to achieving a sustainable peace settlement, Russian Foreign Minister Sergei Lavrov said on Wednesday.