The Armed Forces of Ukraine said that the Russians have sent about 500 troops from occupied areas of the Donetsk and Luhansk regions north into the Kharkiv region, News.az reports citing UNIAN.

Local authorities said there is "a mass withdrawal of Russian troops from the territory of Borova and Bohuslavka in the direction of Kupyansk." 

Kupyansk is an important Russian logistics hub inside Ukraine and may become vulnerable if a Ukrainian counterattack in the region is sustained.

That attack made further progress Tuesday, according to the General Staff of the Ukrainian Armed Forces, with four more settlements to the north and east of Kharkiv falling under Ukrainian control.

CNN has geolocated video from one of those settlements, showing the Ukrainians in control. The new gains put Ukrainian units within a few kilometers of the Russian border in several areas.