“They have settled in the east and south and dictate harsh conditions,” Podolyak added. “So, we certainly can not do without heavy weapons, if we want to unblock the east and Hersonissos and send [back] the Russians as much as possible. “ Last month, the Russian military said the “first phase” of its invasion of Ukraine was complete and that it would withdraw its forces from Kyiv and Chernihiv to focus on the Donbas region in the east of the country. Russia’s announcement of this new phase may in part offer political cover for the Russian military, explaining major defeats in the fighting around Kyiv, but Ukrainian officials have also reported increased military activity and bombing of Donbas by Russian forces. Podolyak referred to an expectation from US and Western officials that Ukraine might need to prepare for further guerrilla warfare – and referred to the Kremlin’s bloody nine-year campaign in support of the Marxist government in Kabul. “Our partners must finally understand that the ‘Afghanism’ they want and the long-running exhausting conflict for Russia will not happen,” he said. The war, which began when Soviet forces invaded in 1979, claimed the lives of nearly a million Afghans and 15,000 Russian soldiers, with another 50,000 wounded. “Afghanization is when there is a strong guerrilla resistance across the country that inflicts heavy losses on the attacker for many months or even years and thus significantly weakens the strength of the occupying army,” Podolyak explained. “Such actions were taken during the Soviet Union’s attempt to take control of Afghanistan: Afghan insurgents destroyed and weakened the Soviet occupiers for years. As a result, they weakened Russia as a whole.” “Russia will leave all Ukrainian territory except the south and east. And it will try to dig there, put on air defenses and reduce the losses of its equipment and personnel sharply,” Podolyak added. The United States is expected to help facilitate the transfer of Soviet-era tanks to Ukraine, a source familiar with the plan told CNN on Saturday. Officials declined to say how many tanks would eventually go to Ukraine. They will be Soviet-era T-72 tanks, which Ukrainian military personnel have experience in handling, a senior US official told CNN. These tanks will be delivered “within days, not weeks,” the official said, from NATO partner countries. The New York Times first reported the transfer. The Ukrainian presidential adviser’s comments came hours after Russia’s ambassador to the United Kingdom, Andrei Kelin, said that if Britain delivered long-range artillery and anti-aircraft systems to Ukraine, it would be a “legitimate target” for Russia. “Any arms deliveries are destabilizing, especially those mentioned by (Ben) Wallace (the British Secretary of Defense),” Kelin was quoted as saying by Russia’s state-run TASS news agency. “They are worsening the situation and making it more bloody.” “Obviously, these are new, rather high-precision weapons. Of course, they will be legitimate targets for our armed forces if they cross the border into Ukraine.” “I have a feeling that London’s idea of what is happening in Ukraine militarily is based on the brave reports of the Ukrainian Ministry of Defense and the Ukrainian leadership,” Kelin said. Russian officials have long complained about the delivery of advanced military weapons to Ukraine by the United States, Britain and other NATO allies, which have provided anti-tank weapons and portable air defenses – some of which have allowed Ukrainian troops to cross the border. Russia advances. CNN’s Kaitlan Collins, Jim Sciutto and Chandelis Duster contributed to this report.