A 72-year-old American man detained in Russia pleaded guilty to fighting as a mercenary in Ukraine, the state-run RIA Novosti news agency reported Monday. Last week, a Moscow court ordered Stephen Hubbard to be placed in pre-trial detention until March 26, 2025. Prosecutors accuse him of having signed a monthly contract with the Ukrainian military after Russia launched its full-scale invasion in February 2022. Hubbard reportedly served in a territorial defense unit in the eastern Ukrainian city of Izium before Russian soldiers captured him in April that same year. “Yes, I agree with the indict…