Ukrainian forces have withdrawn from the eastern town of Avdiivka, where the situation has deteriorated considerably in recent days, General Oleksandr Tarnavsky, who commands the area, said early Saturday, February 17.

It is a significant symbolic victory for Russia ahead of the February 24 anniversary of the start of the invasion, and its most significant territorial gain since it seized Bakhmut last May.

"Based on the operational situation around Avdiivka, in order to avoid encirclement and preserve the lives and health of servicemen, I decided to withdraw our units from the city and move to defense on more favorable lines," Tarnavsky said on Telegram.

"In a situation where the enemy is advancing over the corpses of their own soldiers with a ten-to-one shelling advantage, under constant bombardment, this is the only right decision," he said.

"Encirclement was prevented, personnel were withdrawn, and our soldiers took up defense at the designated lines."

This is the first major decision by Ukraine's new military chief Oleksandr Syrsky following his appointment on February 8, who said it was to preserve the lives of soldiers and prevent their encirclement.

"I decided to withdraw our units from the city and switch to defense on more favorable lines," Syrsky said on Facebook shortly before Tarnavsky's announcement.

"Our soldiers performed their military duty with dignity, did everything possible to destroy the best Russian military units and inflicted significant losses on the enemy," Syrsky said.

Avdiivka, which had around 34,000 inhabitants before the Russian invasion, has important symbolic value.

The industrial city lies in the Donetsk region of Ukraine, which has seen the worst fighting of Russia's nearly two-year invasion and is claimed by the Kremlin to be part of Russia.

It briefly fell in July 2014 into the hands of pro-Russian separatists led by Moscow, before returning to Ukrainian control and remaining so despite the invasion and its proximity to the separatist capital Donetsk.