Russian forces have adopted the tactic of wearing Ukrainian military uniforms on the front lines. But Ukrainian soldiers have invented an algorithm for identifying the enemy, Captain Yuriy Fedorenko,

Russian soldiers wore Ukrainian army uniforms to fight their way into the frontline city of Kupiansk, Kyiv’s military has said. Captain Andrii Kovaliov, a spokesman for the Ukrainian military, said that by disguising themselves as Ukrainian troops the Russian soldiers had committed a war crime.

Kyiv’s military say they have full control of Kupiansk, but admit Russian forces did briefly breach its outskirts