Three-day ceasefire in Ukraine that was unilaterally declared by Russian President Vladimir Putin last month was set to come into effect at 5 p.m. ET on Wednesday (midnight Moscow time), as Russia prepares to mark the anniversary of its World War II Victory Day on Friday.

Victory Day, celebrated on May 9, is Russia’s most important secular holiday, reflecting its wartime sacrifice. But it's also used by the Kremlin to bolster patriotism and regain the superpower prestige it lost when the Soviet Union collapsed in 1991.