Ankle-deep in thick black sludge, Ukrainian President Volodymyr Zelensky moves stealthily with his troops in single file through the warren of trenches and tunnels that form the tense front lines in the east of his country.

Ankle-deep in thick black sludge, Ukrainian President Volodymyr Zelensky moves stealthily with his troops in single file through the warren of trenches and tunnels that form the tense front lines in the east of his country.