Russian defense ministry announced on Saturday that Moscow’s forces had withdrawn from the city of Lyman in Ukraine. Kyiv’s counteroffensive has gained momentum as it takes back more territory that was previously occupied by Russia.

Ukrainian President Volodymyr Zelensky’s chief of staff posted a video on social media confirming the news. The video showed two soldiers standing on a military vehicle attaching the flag with tape to a large sign with the word “Lyman”.

Also Read: Why Lyman is a key area for Ukraine

“We are unfurling our country’s flag and planting it on our land. On Lyman. Everything will be Ukraine”, the Ukrainian soldier said, according to CNN. Lyman is about 160 kilometers (100 miles) southeast of Kharkiv, Ukraine’s second-largest city.

Lyman is known to have strategic importance for Ukraine. It was a key transportation hub before the war broke out. It was later used as the Russian front line for both ground communications and logistics.

With control over the city of Lyman, Ukrainian forces would have to option to push into the Luhansk region. Russian President Vladimir Putin said on Friday that Russia would annex four Ukrainian regions, including Luhansk.

Ukrainian forces encircled the strategic eastern city of Lyman on Saturday. Ukrainian officials said Saturday their forces had surrounded some 5,000 Russian forces who were trying to hold the eastern city of Lyman.

The news came hours after a civilian convoy was attacked in Russia. At least 20 civilians were killed in the attack, which has not been acknowledged by Russian forces.

Also Read: At least 20 dead after civilian convoy attacked in Ukraine: Kharkiv Governor Oleh Syniehubov

In an apparent attempt to secure Moscow’s hold on the newly annexed territory, Russian forces seized the director-general of the Zaporizhzhia Nuclear Power Plant, Ihor Murashov, around 4 PM on Friday, according to the Ukrainian state nuclear company Energoatom.

That was just hours after Vladimir Putin signed treaties to absorb Moscow-controlled Ukrainian territory into Russia, including the area around the nuclear plant.