KYIV, Ukraine (AP) — The Kremlin said Tuesday that there are no prospects for a negotiated end to the war in Ukraine and gave its blessing to efforts to swiftly bring regions already captured under Russia's complete control. Such a move could set the stage for Moscow to escalate the conflict if Ukrainian forces try to take the regions back.

A close ally of Russian President Vladimir Putin, former President Dmitry Medvedev, said that folding the separatist Luhansk and Donetsk regions of eastern Ukraine into Russia itself would make their redrawn frontiers "irreversible" and enable Moscow to use "any means" to defend them.

Pressure within Russia and from Moscow-backed leaders in Luhansk and Donetsk for regional votes that would pave their way to becoming fully Russian has increased in the wake of a Ukrainian counteroffensive — bolstered by Western-supplied weaponry — that is wresting back large areas of previously Russian-occupied territory.

Moscow-backed leaders in the Russian-occupied Kherson region of southern Ukraine and pro-Russia activists in the partly-occupied Zaporizhzhia region on Tuesday joined earlier calls from separatist authorities in Luhansk and Donetsk for speedy referendums on joining Russia.

Such votes would almost certainly go Moscow's way. The succession of appeals and Medvedev's backing for them suggested stiffening determination in the Kremlin to fend off further territorial gains by Ukraine.

Kremlin spokesman Dmitry Peskov said Tuesday that there are no prospects for a diplomatic settlement. Medvedev, the deputy head of Russia's Security Council chaired by Putin, said on his messaging app channel that votes in separatist regions are important to protect their residents and "restore historic justice" and would "completely change" Russia's future trajectory.

"After they are held and the new territories are taken into Russia's fold, a geopolitical transformation of the world will become irreversible," said Medvedev, who also served as Russia's president from 2008-2012.

"An encroachment on the territory of Russia is a crime that would warrant any means of self-defense," he said, adding that Russia would enshrine the new territories in its constitution so no future Russian leader could hand them back.

"That is why they fear those referendums so much in Kyiv and in the West," Medvedev said. "That is why they must be held."

The recapturing of large areas of previously Russian-occupied territory, most notably in the northeastern Kharkiv region, has strengthened Ukraine's arguments that its troops could deliver more stinging defeats to Russia with additional armament deliveries.

More heavy weaponry is on its way, with Slovenia this week promising 28 tanks and Germany pledging four additional self-propelled howitzers. More aid also is expected from Britain, already one of Ukraine's biggest military backers after the United States. British Prime Minister Liz Truss is expected to promise that in 2023, her government will "match or exceed" the 2.3 billion pounds ($2.7 billion) in military aid given to Ukraine this year.

The swiftness of the Ukrainian counteroffensive also saw Russian forces abandon armored vehicles and other weapons as they beat hasty retreats. Ukrainian forces are recycling captured weaponry back into battle. A Washington-based think tank, The Institute for the Study of War, said Tuesday that abandoned Russian T-72 tanks are being used by Ukrainian forces seeking to push onward into Russian-occupied Luhansk.

In the counteroffensive's wake, Ukrainian officials found hundreds of graves near the once-occupied city of Izium. Yevhenii Yenin, a deputy minister in Ukraine's Internal Affairs Ministry, told a national telecast that officials found many bodies "with signs of violent death."

"These are broken ribs and broken heads, men with bound hands, broken jaws and severed genitalia," he said.

Ukrainian officials also have alleged Russian forces tortured people in occupied areas, including shocking them with radio telephones dating back to the Soviet era. Russia has repeatedly denied abusing or killing prisoners, though Ukrainian officials found mass graves around the city of Bucha after blunting a Russian offensive targeting the capital, Kyiv, at the start of the war.

Meanwhile, a Ukrainian push continues in the south of the country. Ukraine's southern military command said early Tuesday its troops sank a Russian barge carrying troops and weapons across the Dnipro River near the Russian-occupied city of Nova Kakhovka. It offered no other details on the sinking of the barge in the Russian-occupied Kherson region, which has been a major target in the Ukrainian counteroffensive.

In other developments:

— Moscow has likely moved its Kilo-class submarines from their station on the Crimean Peninsula to southern Russia over fears about them being struck by long-range Ukrainian fire, the British military said Tuesday. In a daily intelligence briefing, the British Defense Ministry said those submarines had "almost certainly" been moved to Krasnodar Krai in mainland Russia, instead of a naval base at Sevastopol on the Crimean Peninsula.

— McDonald's eateries in Kyiv were to begin serving again Tuesday for the first time since Russia invaded in February. Three restaurants planned to offer delivery service only initially, marking a step of sorts back toward the life Ukrainians knew before the war, which enters its seventh month later this week.

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