“After a month of fierce fighting and significant losses in the Kupiansk and Lyman directions, the enemy is regrouping its forces and means, simultaneously throwing newly formed brigades and divisions from the territory of the Russian Federation,” Syrskyi said in his Telegram channel.
Syrskyi said that the main goal of these measures was to “increase the level of combat potential and resume active offensive operations”.
Syrskyi did not provide details of the Russian regrouping but said the forces continued heavy artillery and mortar shelling and air assaults.
“Under such conditions, we must promptly take all measures to strengthen our defences on the threatened lines and advance where possible,” the general said.
Kupiansk, a town with a pre-war population of around 27,000, was seized by Russia in the early days of the February 2022 invasion before Ukrainian troops recaptured it in a lightning offensive last September that embarrassed Moscow.
Regional authorities announced a mandatory evacuation of civilians from near the Kupiansk front earlier this month due to daily Russian shelling.
Reuters could not independently verify the battlefield reports.
(Reporting by Oleksandr Kozhukhar in Kyiv; Editing by Cynthia Osterman)