1st Ukrainian city falls since the US became deadlocked in sending more military aid

LONDON -- On the same day Alexey Navalny was declared dead in a Russian prison, Vladimir Putin was able to rack up another victory of sorts as Ukraine's military announced it has retreated from the key city of Avdiivka in eastern Ukraine, ceding it to Russia after months of ferocious fighting that cost tens of thousands of Russian casualties.

Avdiivka is the first notable Ukrainian city to fall to Russia since Bakhmut nearly a year ago. It was a small city with 32,000 inhabitants that has been on the frontline since 2014. Russia has now reduced it to a few skeletal ruins.

It is also the first Ukrainian city to fall since the U.S. became deadlocked in sending more military aid.

Russia's Defense Minister Sergei Shoigu said Saturday that Russian forces have taken complete control of Avdiivka.

Shoigu told the Kremlin that Russian forces were now working to clear the final pockets of resistance at the Avdiivka Coke and Chemical Plant.

Videos on social media Saturday seen by ABC News' Ukraine team appeared to show soldiers raising the Russian flag over one of the plant's buildings.

Ukrainian forces had held off a huge Russian offensive there since October but as severe ammunition shortages have bitten amid the reduction in Western aid, Russia was able to restore a huge advantage in artillery and airstrikes, allowing it to grind through the defenses and effectively level the city.

In the past two weeks, Russia had managed to finally make significant advances in the north and south, closing in on the encirclement of Avdiivka. Ukrainian troops had no choice but to withdraw or risk being surrounded meaning the withdrawal should prevent the loss of more troops and equipment.

In many ways it was extraordinary Ukraine had held Avdiivka since the start of Russia's full-scale invasion -- partly the result of how heavily fortified it was -- but it now underlines how the initiative is now in Russia's hands.

Most military analysts do not believe Avdiivka's fall will have an immediate major impact on Ukraine's overall position because it will be difficult for Russia to advance further from it, just as it has been from Bakhmut.

Ukraine is focusing on regrouping their remaining troops, replenishing supplies and arranging units in new strategic positions, according to Commander of the Tavria direction Gen. Oleksandr Tarnavskyi.

Meanwhile, a U.S. official briefed last week said that Ukraine may face "catastrophic" shortages of ammunition by March if Congress doesn't authorize more aid to the embattled country.

Russia has suffered enormous losses to reach this point, however, with losses estimated upward of as many as 20,000 killed and injured since October and over 1,000 armored vehicles since the beginning of its offensive against Avdiivka in October 2023.