KYIV, Ukraine (AP) — Ukraine launched one of the biggest drone attacks on the Moscow-annexed Crimean Peninsula since the full-scale war that started with Russia’s invasion 21 months ago, Russian officials said Friday.

At the same time, Ukrainian officials reported that the Kremlin’s forces escalated their weekslong and costly attempt to storm Avdiivka, a strategically important city in eastern Ukraine.

The stepped-up efforts came as both sides are keen to show they are not deadlocked as the fighting approaches 2024. Neither side has gained much ground despite a Ukrainian counteroffensive that began in June, and analysts predict the war will be a long one.

With winter weather setting in, bringing snow and freezing temperatures to the battlefield, Ukraine and Russia are looking to take ground that could provide platforms for future advances.

The Moscow-appointed governor for the Russian-occupied part of southern Ukraine’s Kherson region, Vladimir Saldo, said Ukraine launched a major drone attack on Crimea early Friday. He claimed that dozens of drones were shot down over the province and the northern part of Crimea.

Russia annexed the peninsula from Ukraine in 2014, a move that most of the world considered illegal, and has used it as a staging and supply point during the war.

The Russian Defense Ministry said air defenses downed 13 Ukrainian drones over Crimea and three more over southern Russia’s Volgograd region.

It was not possible to independently verify either side’s battlefield claims.

Russia has been trying to capture Avdiivka since Oct. 10, using heavy bombardments and reportedly taking heavy losses. The city is wrecked, and the battle has become reminiscent of the fight over the eastern Ukraine city of Bakhmut, which was largely destroyed during nine months of fighting before Russian troops eventually captured it.

Avdiivka lies in the northern suburbs of Donetsk, a city in a region of the same name that Russian forces partially occupy. Avdiivka’s location grants Ukrainian forces artillery advantages over the city and could serve as a springboard for them to liberate Donetsk.

After intense artillery and aerial bombardments, Russian troops attacked the heavily fortified city from an additional direction and spread along the line of contact whereas before they attacked in columns, Vitalii Barabash, the head of Avdiivka’s military administration, said Friday.

The city is enduring up to 40 bombardments daily, he said.

___

Follow AP’s coverage of the war in Ukraine at https://apnews.com/hub/russia-ukraine