However, the Ukrainians surprised the Russians and the world by launching a fast-paced counteroffensive in the east around Kharkiv, Ukraine's second-largest city.The fact that the Russian high command had decided to mass considerable forces in the south to defend Kherson, which Moscow ended up retreating from in November, aided Kyiv's counteroffensive, which sliced through Russian lines like a hot knife through butter and repeatedly flanked large Russian formations — including at a major logistical hub in far eastern Ukraine.While the brigade's size is classified, the BBC said that 75% of the unit's troops may have been killed or wounded so far, based on estimates of attrition for Russian units in Ukraine.Stavros Atlamazoglou is a defense journalist specializing in special operations, a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ), and a Johns Hopkins University graduate.He is working toward a master's degree in strategy and cybersecurity at the Johns Hopkins' School of Advanced International Studies."