In the midst of Ukraine’s current difficult military situation in its defence against the Russian invasion, Ukrainian President Volodymyr Zelensky has dismissed several advisers. One of the people affected is Zelensky’s assistant Serhiy Shefir, who had held the post since 2019, according to a decree published on Saturday. A press spokesman justified the dismissals with an “optimization of personnel” in the presidential office, Ukrainian media reported. Zelensky has replaced some high-ranking officials several times in recent months. A particular stir was caused in February when the commander-i…