Ukraine’s President Volodymyr Zelensky sacked his top security agency head and top prosecutor after it emerged that more than 60 employees had been “working against” Ukraine in Russian-occupied territory. Zelensky said at least 651 cases of treason and collusion have been opened against the officials, posing “very serious questions” for those in charge. Prosecutor-general Iryna Venediktova and security chief Ivan Bakanov were both close colleagues and friends of Zelensky. Some analysts say the information passed on by the employees could explain Russia’s quick capture of large areas of the country’s south in the first week of its invasion. Meanwhile, according to officials, Russia is preparing for its next offensive stage as it eyes the strategic eastern city of Sloviansk. Russia is also reinforcing its defensive positions across the occupied areas in the country’s south after Ukraine pledged to regain the territory last week.