Pro-Russian rebels in eastern Ukraine paraded dozens of captured soldiers before a jeering crowd yesterday in mockery of Independence Day celebrations in the capital.
Ukraine's pro-Western government had sought to boost morale with an upbeat military parade to mark the country's independence from the Soviet Union in 1991.
Speaking to a crowd of thousands in Independence Square, known locally as the Maidan, President Petro Poroshenko decried Russian "aggression" and said he was "convinced that the battle for Ukraine, for independence, will be our success".
But it was markedly different scene in the eastern rebel stronghold of Donetsk, where about 40 or 50 captured government soldiers were paraded through the city's central Lenin Square as onlookers hurled garbage and empty bottles at them.
"You are killing children!" screamed some in the crowd at the prisoners, who walked with heads bowed and their hands behind their backs before being placed on two buses and taken to an unknown destination.
Human Rights Watch deputy director Rachel Denber said on Twitter that the event amounted to "humiliating and degrading treatment" of prisoners and was therefore in breach of the Geneva Convention.
Ukraine and the West blame Russia for supporting the separatist insurgents still clinging on to territory after four months of fighting in the restive east. Poroshenko pledged to spend an extra 40 billion hryvnia (HK$22.6 billion) by 2017 on its army over the next three years for the purchase of warplanes, warships and helicopters.
He called it "only the modest beginning" of the rebirth of the Ukrainian military.
Kiev's conflict with the pro-Russian rebels in the separatist regions of Luhansk and Donetsk has claimed more than 2,200 lives since April.