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.

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

The Ukrainian president claimed he was ready to travel to Turkey to meet with Russia’s leader, but he also insisted on an immediate truce before negotiations can begin.