The attacks came a day before a Russian-proposed cease-fire was to take effect and as Moscow prepared to welcome foreign dignitaries for a parade.

Moscow's grand avenues, like every year in early May, were taken over by the growling of 80-year-old tanks and the smell of gasoline burned by military vehicles. To the delight of many locals, soldiers marched in multiple rehearsals for the May 9 Victory Day Parade in the week leading up to the actual event.

Chinese President Xi Jinping told Russia's Vladimir Putin on Thursday their two countries should be "friends of steel", as they pledged to boost cooperation to a new level at a time of heightened confrontation with the West.