Leonid Onyshchenko, a gruff-voiced 63-year-old Ukrainian soldier with a thick moustache, has spent many a Christmas away from his family, but hearing his little grandson Petro's voice over the phone from far away is as hard as ever.
Onyshchchenko joined the territorial defence force after Moscow's February invasion, and has volunteered supporting Ukraine's army in the fight against Russian-backed separatists in the country's east since 2014.
