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

Russia has not yet said who it will send to Istanbul on Thursday and has refused to respond to ultimatums.

President Volodymyr Zelensky said he will meet with Turkish President Recep Tayyip Erdogan in Ankara, but said both leaders are ready to fly to Istanbul if Russian President Vladimir Putin chooses to attend the talks there.