At approximately 11:45 am on June 7, 2019, while operating in the Philippine Sea, a Russian Destroyer (UDALOY I DD 572) made an unsafe maneuver against USS Chancellorsville (CG-62), closing to within 50-100 feet and putting the safety of her crew and ship at risk. While Chancellorsville was recovering its helicopter on a steady course and speed, the Russian ship DD572 maneuvered from behind and to the right of Chancellorsville, accelerated and closed to an unsafe distance of within 50-100 feet. This unsafe action forced Chancellorsville to execute all engines back full and to maneuver to avoid collision. The Russian ship’s actions were unsafe and unprofessional, and not in accordance with the International Regulations for Preventing Collisions at Sea (COLREGS), "Rules of the Road," and internationally recognized maritime customs.