Fierce fighting is taking place around the eastern city of Avdiivka Ukraineafter Moscow launched one of its largest military operations in the region in many months.

Ukrainian President Volodymyr Zelensky said Ukrainian soldiers were holding their positions in the third day of fighting. However, local municipality officials said the Russian attacks are unrelenting.

According to Kiev, Moscow has deployed strong forces and sent a lot of equipment to the Avdiivka region to show it can fight back, after four months of pressure on the eastern and southern fronts.

“Avdiivka. We hold our positions. Ukrainian courage and unity will determine how this war will end,” Zelensky wrote in a Telegram post that was accompanied by photos of Ukrainian soldiers and a sign with Avdiivka’s name at the entrance to the city.

Ukrainian Special Operations Forces claimed that Kiev “thwarted the plans of the maddened enemy, repulsed all attacks and is holding its positions.”

Vitaly Barabas, the city’s mayor, told Ukrainian television: “The enemy is not stopping the barrage of fire, it is coming from all directions.”

Abdiivka is home to a large coke factory and is a short distance from Donetsk, the Russian-controlled city in the province of the same name. It has become a symbol of the Ukrainian resistance since Ukrainian forces defended it long before Russia’s February 2022 invasion against pro-Russian separatists who took control of the Donetsk and Luhansk territories in 2014. Before war had 32,000 inhabitants, but now there are only 1,600 left. Barabas explained that the continuous bombardment prevents the organized exodus of the residents.

Russia’s Defense Ministry claimed that its forces inflicted heavy blows on Ukrainian forces in various areas, including Avdiyvka, but gave no further details.

Oleksandr Stupun, a spokesman for Ukrainian forces on the southern front, said Russia sees Avdiivka as an opportunity to achieve a major victory and “turn the tide” of the war. “Today the capture or encirclement of Abdiivka is probably the best they can achieve at this stage,” he said.

The Institute for the Study of War (ISW), a US-based non-profit research group, said Russia appeared to have advanced into some villages southwest and northwest of Abdiivka this week. But the encirclement of the city will probably require more forces than he has allocated for this enterprise.

Russia is also stepping up airstrikes on Danube ports in the region south of Odessa. A military spokeswoman said a grain silo was hit overnight and some of the products stored there were destroyed. Ukraine also claims to have thwarted an attempt by eight Russian saboteurs to cross its border into the Sumy region in the northeast.