Ukraine said on Monday troops defending the country’s second-largest city, Kharkiv, had repelled Russian forces and advanced as far as the border with Russia.

Reuters could not immediately verify Ukraine’s battlefield account and it was not clear how many troops had reached the Russian border and where.

If confirmed, it would suggest a Ukrainian counter-offensive is having increasing success in pushing back Russian forces in the northeast after Western military agencies said Moscow’s offensive in the Donbas region had stalled.