Aformer Ukrainian presidential adviser has described Kyiv’s stalled counter-offensive as a “disaster” and accused Volodymyr Zelensky of making strategic mistakes. Oleksiy Arestovych said that Mr Zelensky and his military commanders have failed to break through Russian lines and that Ukraine now needed a new leader. “They are not telling the truth. There will be no return to the borders of 1991, and there will be no Crimea in the near future,” he said. Mr Arestovych resigned in January as a presidential adviser after a row over the effectiveness of Ukraine’s air defence systems. This week, Ukrainian prosecutors opened an investigation...