Russian President Vladimir Putin said Tuesday that Russia and Ukraine had made a “serious breakthrough” during discussions in Istanbul, Turkey, but that the situation had changed “dramatically” after Russia was accused of crimes in the Ukrainian town of Bucha.

“In Istanbul, we managed to achieve a serious breakthrough, because our Ukrainian colleagues did not associate the requirements of security, international security of Ukraine, with such a concept as internationally accepted borders of Ukraine … But, unfortunately, after reaching agreements and after our clearly demonstrated intentions to create conditions for favorable conditions for the continuation of negotiations, we encountered a provocation in the village of Bucha, to which the Russian army has nothing to do,” Putin remarked while appearing in Moscow alongside United Nations Secretary General Antonio Guterres.

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“And the position of our negotiators from Ukraine on a further settlement, it changed dramatically after that. They departed from their previous intentions to put aside the issues of security guarantees and the territories of Crimea, Sevastopol and the republics of Donbass. They just gave up on it,” he continued.

Guterres recommended forming a three-party humanitarian group comprised of the United Nations, Russia, and Ukraine to coordinate cooperation on evacuation corridors in Ukraine.

On Saturday, Ukrainian President Volodymyr Zelensky stated that future negotiations in Turkey are dependent on Putin, while also expressing his willingness to join in talks.

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Mykhailo Podolyak, Zelensky’s adviser, said Thursday that the war in Ukraine “can end in direct talks” between Zelensky and Putin, but he added that he was waiting to see how Russia’s military push in Ukraine’s east progressed in the following days.

After photographs and allegations of summary executions, cruelty, and indiscriminate shelling emerged in the aftermath of Russia’s quick retreat, as the Kremlin switched its focus away from the Ukrainian capital and to the country’s east, Bucha became a byword for war crimes.

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Moscow alleged, without providing evidence, that the crimes in Bucha were “fake” and were part of a “planned media campaign.” However, according to witnesses who spoke to CNN, the bloodshed in the village began weeks before. Since the beginning of the war, there have also been reports of looting, disappearances, and proof of indiscriminate killings of people.