(Reuters) – Russian forces relied heavily on aerial attacks on Thursday in their slow-moving campaign to win control of eastern Ukraine and resorted to new smaller attack groups in pressing to capture the beleaguered town of Avdiivka. Moscow has focused its attention on the eastern regions of Donetsk and Luhansk since failing to advance on Kyiv in the early days of the February 2022 invasion of Ukraine. It has set its sights since mid-October on Avdiivka, a gateway to the Russian-held regional centre of Donetsk — 20 km (12 miles) to the east. The town has resisted capture while coming under s…