Russian President Vladimir Putin on Thursday said his main aim in Ukraine after 30 months of fighting was to capture the eastern Donbas area and claimed that Ukraine's Kursk counter-offensive had made that easier.Putin was speaking a day after Russia attacked Ukraine's western Lviv region with deadly strikes, and after recent advances by Moscow's forces in the Donbas.Since the start of its offensive in February 2022 when it failed to capture the Ukrainian capital Kyiv, Russia has adapted its aims, concentrating instead on trying to conquer eastern Ukraine.While Ukraine's surprise push into Russia's Kursk region last month caught Russian forces off-guard, Putin stressed that the move had failed to slow Moscow's advance in occupied Ukraine."The aim of the enemy [in Kursk] was to force us to worry, hustle, divert troops and to stop our offensive in key areas, especially in the Donbas, the liberation of which is our main primary objective," Putin said at a forum in Vladivostok, in Russia's Far East.Russia claims as its own the eastern Donetsk region and three other Ukrainian regions.Moscow has advanced strongly this summer and its troops are now around a dozen kilometers from the city of Pokrovsk a key logistics hub in east Ukraine from where thousands have now fled.Putin said that by sending "quite well-prepared units" into Kursk, Ukraine had made Moscow's advance in Donbas quicker."The enemy weakened itself in key areas, our army has accelerated its offensive operations," he argued.'Holy duty'Putin also claimed that Moscow's army has begun to push out Ukrainian forces from the Kursk region, where Kyiv's troops have held on to towns and villages for almost a month."Our armed forces have stabilized the situation and started gradually squeezing [the enemy] out from our territory," Putin said.It was not possible to verify those claims.Ukrainian President Volodymyr Zelensky insisted on Thursday that Ukraine was "maintaining the defined lines" in the Kursk region.Russia did not mount a large-scale response in the first days of the incursion, which became the largest on Russian soil since World War II.Putin has since played down the significance of the Ukrainian attack but has hardened his rhetoric in recent days."It is the holy duty of the Russian army to do everything to throw out the enemy from this territory and to protect our citizens," he said on Thursday.Earlier this week, Zelensky told United States TV channel NBC that Ukraine would hold on to the territory captured in the Kursk region.Zelensky has previously said that one of Kyiv's "goals" in Kursk was to show Russians "what is more important to him (Putin): occupation of the territories of Ukraine or the protection of his population."Kyiv has also said that it wants to force Moscow into "fair" negotiations.Aborted dealWhile Russian officials have rushed in recent weeks to say that the Kursk incursion makes any talks with Ukraine impossible, Putin appeared to roll back those statements.Russia was ready to talk, he said but on the basis of an aborted deal reached in Istanbul in 2022, the details of which were never made public by either side.But Putin has repeatedly said that Moscow can only negotiate with Ukraine if Kyiv surrenders four of its regions Donetsk, Luhansk, Zaporizhzhia and Kherson."Are we ready to negotiate with them? We have never refused to do so," Putin said on Thursday."But not on the basis of some ephemeral demands, but on the basis of those documents that were agreed and actually initialed in Istanbul," he added.The Kremlin has claimed Russia and Ukraine were on the verge of a deal in the spring of 2022, shortly after Moscow launched its offensive in Ukraine.On Thursday, both sides reported fresh casualties near the frontlines.In Ukraine's Donetsk region, a 74-year-old man died when a Russian shell hit his home in the town of Kostyantynivka, the regional prosecutor's office said, posting a photo of a destroyed building.Ukrainian shelling killed a man in Russia's Belgorod border region, the region's Governor Vyacheslav Gladkov said on Telegram.