Mariupol, Ukraine – The huge troop-transport helicopter dates from the Soviet era. It flies just above the tree line, nose down, to avoid Russian radar. After two hours of flying over smooth ground, frozen lakes and ruined villages in the dark winter night, we arrive here at the headquarters of the Navy Guard, where we meet the officers who for six years have led the fight against pro-Russian separatists in the Donbass region.

Read more here.