Drone strikes on Russian soil are only set to increase as Ukraine brings Moscow's invasion home, a senior Kyiv official has said. Mykhailo Podolyak, an adviser to President Volodymyr Zelensky said that it has increased strikes on Russian-occupied areas and would also ramp up attacks within Russia itself. Kyiv does not generally directly claim attacks outside of Ukraine, with Mr Podolyak saying such strikes would be carried out by "agents" or "partisans". "As for Russia... there is an increasing number of attacks by unidentified drones launched from the territory of the Russian Federation, and the number of these attacks will increase," Mr Podolyak told Reuters. "This is the stage of the war when hostilities are gradually being transferred to the territory of the Russian Federation". Drone attacks on Russia have increased sharply recently, with the largest such strikes hitting six regions on one night this week. That assault included two Russian military transport planes being destroyed – and two more damaged – at an airbase in the city of Pskov. Ukraine's military intelligence chief, Kyrylo Budanov, said that the drones were launched from inside Russia. However, in speaking to the War Zone website, Mr Budanov did not say whether the attack – about 400 miles (700 kilometres) from the Ukraine border – was carried out by Ukrainian or Russian operatives. "We are working from the territory of Russia," he said. President Zelensky had suggested earlier this week that a new long-range Ukrainian weapon had hit a target 700 kilometres away, without saying what the weapon was or where it struck. The drone strikes continued into Thursday, with attacks on three regions. Russia's Defence Ministry also claimed to have destroyed a total of 281 Ukrainian drones over the past week, including 29 over the western regions of Russia – indicating the scale of the role drones are now playing in the 18-month war. On the ground in Ukraine, where Kyiv is trying to break through Russian lines in a counteroffensive that started in June, The US said on Thursday that it has seen solid progress by Ukrainian forces in the southern Zaporizhzhia region in the last 72 hours. "We have noted over the last 72 hours or so some notable progress by Ukrainian armed forces ...in that southern line of advance coming out of the Zaporizhzhia area, and they have achieved some success against that second line of Russian defenses," White House National Security Council spokesman John Kirby said. "That is not to say... that they aren't mindful that they've still got some tough fighting ahead of them as they try to push further south" or that Russia could launch a counter effort, he added. Mr Podolyak said Kyiv's forces were continuing to advance and hoped that Western military aid would continue to come in the months ahead. He added that he believed allies, who have poured in billions of pounds of weaponry, understood that there could be no kind of "compromise" with Moscow. "At the moment, the partners understand that this war will no longer end in a compromise solution - that is, either we destroy Russia's capabilities by military means, and to do this we need the appropriate tools, or this war with such level of aggression will continue for some time." The Kremlin will not like the pressure Kyiv is exerting with its drones strikes. That may have been behind the state-run RIA news agency quoting the head of Russia's space agency Roscosmos as sayng that the country's Sarmat intercontinental ballistic missiles, which are capable of carrying ten or more nuclear warheads, had been put on combat duty. Mr Kirby said that the White House was not in a position to confirm the reports. In June, Vladimir Putin said that Sarmat missiles would be deployed for combat duty "soon". The Russian president has constantly sought to talk up the advanced nature of the missiles in recent years. Reuters and Associated Press contributed to this report Read More The ‘Vampire’ rocket system helping Ukraine shoot down Russia’s kamikaze drones Ukraine-Russia – live: Putin puts ‘Satan II’ nuclear missile ‘on combat duty’ as Kyiv launches drone strikes Ukraine launches ‘massive’ drone strikes on six regions of Russia – destroying war planes The Body in the Woods | An Independent TV Original Documentary The harrowing discovery at centre of The Independent’s new documentary