Russia claimed on Friday that its forces had “completely liberated” the Azovstal steel plant in Mariupol – the last stronghold of the Ukrainian resistance in the once-Russian southern city.

CNN cannot independently verify that all Ukrainian troops have left the steel plant.

Ukraine has not yet confirmed Russia’s claims, which, if true, would represent a symbolic military victory for Moscow.

Here’s what you need to know:

Siege of Mariupol: The strategically important port city was one of the first to come under Russian attack after the start of the invasion of Moscow on February 24. By early March, it had been besieged by Russian forces, leaving the population facing severe shortages of food and water – and constant bombing that hit a maternity hospital and a theater where civilians were sheltering.

the plant: By mid-April, most of the last Ukrainian defenders were fighting to repel Russian forces from the Azovstal steel plant – which had also become home to up to 1,000 civilians, including some seriously wounded and stranded without medical attention.

In late April, Russia claimed to have achieved the “liberation” of Mariupol – which Ukrainian President Volodymyr Zelensky denied, saying soldiers were still fighting back in the city.

Evacuation Attempts: Evacuations of civilians from Azovstal began on 1 May. On May 16, the Ukrainian military said its forces had completed their “combat mission” at the steel plant, where hundreds of soldiers had been evacuated from the facility.

The Russian Defense Ministry said hundreds of Ukrainian soldiers who had been evacuated from the factory were taken to a pre-trial detention center, while the seriously injured were receiving medical treatment.

Ukraine has said it expects to exchange Russian prisoners of war for seriously wounded soldiers.

situation on the ground: If true, Russia’s claim on Friday indicates that the entire city of Mariupol has fallen under Russian control after nearly three months of brutal fighting.

A spokesman for the Russian Defense Ministry claimed that “the last group of 531 militants surrendered” at the plant. And earlier, the Ukrainian commander of the Azov regiment issued an order to the soldiers to preserve “their life and health … and stop defending a city.”

Videos posted online show the remaining Azov fighters leaving the steel plant. CNN cannot independently verify how many fighters are left at the plant.

Russian gains: If the fall of the Azovstal steel plant is confirmed, this means that the Russian forces are in complete control of Mariupol, paving the way for them to create a land corridor between Russia and the annexed lands of Crimea.

A symbolic victory for Russia would also secure a major port on the Sea of ​​Azov and release Russian forces to fight on the front lines of the war in the Donbass region.