Russian troops are inching towards the city of Kostiantynivka in Ukraine’s eastern Donetsk region, trying to establish a foothold close to a heavily defended area, Ukraine’s top army official said on Saturday.Kostiantynivka, along with other cities, forms a so-called fortress belt in the country’s east – an area well-fortified by the Ukrainian military.“We are repelling the Russian occupiers’ persistent attempts to gain a foothold in the outskirts of Kostiantynivka using infiltration...