Ukrainian forces have surprised Russian troops at Balakliya near Kharkiv in the east, after much of the Kremlin's strength had been redeployed to the south.
Presidential adviser Oleksiy Arestovych said: "The Russians are saying that Balakliya is encircled when in fact (our troops) have gone much further... they've cut off the road to Kupiansk," he said, referring to the main transport hub supplying Russian forces in Izyum to the east.
A pro-Russian official from the region, Rodion Miroshnik, said on Telegram that Balakliya remained in Russian hands although there was fighting north of the town.
Reuters was unable to verify the battlefield accounts but Yuri Podolyak, a Ukrainian often quoted by pro-Russian officials, also said Russian troops were surprised by the Ukrainian advance.
"The enemy had considerable success near Balakleiia with a relatively small force... It would appear that Russian forces slept through this advance and were expecting it elsewhere," he wrote on Telegram.
"Everything would seem to depend now on the speed with which reserves are brought into the fight... there have been significant losses."
Torej odvisni so od dotoka "robe", kar pa jih jebe, ker so jim himarsali povezave?