The United Nations is reviewing reports that Ukrainians may have executed 10 Russian prisoners of war after videos authenticated by The New York Times appear to show a line of Russian soldiers that had been killed at close range.The grisly videos, first posted on Ukrainian news sites and social media channels, do not show the killings, but before-and-after scenes of Russian soldiers lying on the ground in a line, appearing to have been shot dead at close range, The Times reported.On Ukrainian channels, the videos were shared as examples of the country's successful defense against Russian invaders, according to The Times.According to a statement posted to Telegram by a spokesperson for the Russian Ministry of Foreign Affairs, the clips are "further evidence of the crimes committed by Ukrainian neo-Nazis."Allegations of war crimes — including rapes, torture, and executions — have been reported against both Russians and Ukrainians since Russia's unprovoked invasion in February, though Matilda Bogner, head of the UN Human Rights Monitoring Mission in Ukraine, told Reuters the mistreatment of Ukrainian prisoners by Russians appears "fairly systematic" while it is "not systematic" for Ukraine to mistreat Russian soldiers."