Kyiv has opened a criminal investigation into what it said was Russia's "brutal and brazen shooting of an unarmed person" depicted in a video spread on social media and prompted a public outcry in Ukraine.
The 12-second video, which rapidly amassed shares on Twitter, shows an apparently unarmed man in a uniform with a Ukrainian flag insignia on his arm standing and smoking a cigarette in a wooded area.
The man says "Slava Ukraini!" - or Glory to Ukraine - before multiple shots are heard coming from an unseen shooter or shooters. The man slumps to the ground as bullets appear to hit his body. A voice is heard saying "Die, bitch" in Russian.
The "Glory to Ukraine" phrase and the response "Heroyam Slava", or "Glory to the Heroes", has been a hallmark of post-Soviet Ukraine, but it has taken on special significance as a common greeting in public life since the start of the war. It has also served to rally international support for Ukraine.
Reuters was not immediately able to verify the authenticity, date or location of the video, which is of poor quality. Russia's Defense Ministry did not immediately respond to a query about it.
The man was quickly hailed by Ukrainians as a hero across social media, where many users posted "Heroyam Slava" in response.
A prominent lawyer who had been wounded while fighting in eastern Ukraine last year said he was collecting money for a reward to anyone who identified those responsible. He personally pledged $1,000.
Ukrainian authorities did not say where or when the shooting occurred.
Ukrainian President Volodymyr Zelenskiy, noting that the video had appeared on Monday, said it showed Russian occupiers brutally killing a soldier.
"I want us all in unity to respond to his words, 'Glory to the hero. Glory to the heroes. Glory to Ukraine.' And we will find the murderers," he said.
Within hours, #GloryToUkraine became one of the top trending hashtags on Twitter.
Andriy Kostin, Ukraine's prosecutor general, said on Telegram that Ukraine's security service had registered the shooting as a criminal case under a part of the country's criminal code that covers violations of war laws and customs.
"Even the war has its own laws," he said, adding that prosecutors from his office would lead the case.
"There are rules of international law systematically ignored by the Russian criminal regime. But sooner or later, there will be punishment."
The head of Ukraine's presidential office, Andriy Yermak, said the man was a Ukrainian prisoner of war and that the incident was part of a "deliberate policy of terror" by Russia.
"The murder of a captive is the latest Russian war crime," Yermak wrote in a tweet. "For every such war crime there will be retribution."
Ukrainian and Western authorities say there is evidence for thousands of war crimes committed in Ukraine since Russia invaded in February 2022. Russia has repeatedly denied that its forces have committed atrocities or attacked civilians.
"Before his death, (the man) reminded all of us of the meaning of the words 'Glory to Ukraine!" Ukrainian Deputy Prime Minister Iryna Vereshchuk said on Telegram.
"And I also want every occupier before their death to remember this photo: a Ukrainian soldier with a cigarette and a fearless look."