A spy inside Russia’s army. The Wall Street Journal tells the story of the lieutenant who helped Ukraine kill hundreds of his fellow soldiers.

Lev Stupnikov came to public attention in September 2025. In an interview that month with Ukrainian YouTuber Dmytro Karpenko, he revealed that he was a Russian officer sent to fight in Ukraine who had spent more than six months supplying Ukrainian forces with targeting information to help them strike his fellow soldiers. RT said more than 200 Russian soldiers had died because of him. Chechen special forces announced a manhunt for Stupnikov, who by then had crossed the front line and was fighting...