Ukraine’s President Volodymyr Zelensky raised the stakes ahead of a potential meeting with Vladimir Putin in Turkey by saying he wouldn’t hold talks with any Russian representative other than the president himself.

Russian President Vladimir Putin proposed direct peace talks with Ukraine on May 15 in Istanbul, Turkey. The talks, he said, would aim to bring “a durable peace” and address the root causes of the war that began in February 2022 when Russia invaded Ukraine.

The new round of negotiations comes amid a long history of delaying tactics by the Russian side as the fighting in Ukraine grinds on.