In what could be an effective announcement of withdrawal, Russia's defense ministry says its troops will be regrouped from a key strategic area in eastern Ukraine amid fierce counter-offensives by Ukrainian forces. President Volodymyr Zelenskyy has pledged that Ukraine will continue its counter-offensive.

Russian officials announced on Saturday that Russian troops will be regrouped from Izyum areas in the Kharkiv region to strengthen operations in the Donetsk region.

Ukraine's security service said on the same day that Ukrainian troops had taken control of Kupiansk in the Kharkiv region, which lies on Russia's supply routes to the Donbas frontline.

Andriy Yermak, the head of Ukraine's presidential office, posted photos on social media showing Ukrainian forces outside Izyum.

Izyum is believed to be an important base for Russia to deploy and deliver supplies to its troops in the Donbas region. If Ukraine retakes control of Izyum, it will likely deal a heavy blow to Russia.

Zelenskyy notes in a video released on Saturday that as part of active actions since the beginning of September, about 2,000 square kilometers of Ukraine's territory have been liberated.

He does not specifically mention Izyum. But he says that the nearby Donetsk region will be liberated.