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.

The talks took place in the warring capitals of Moscow and Kyiv, from Washington and Riyadh, Saudi Arabia, to countries across Europe.

The talks in Istanbul complicated a European push for the U.S. to pressure Russia an into a ceasefire in Ukraine, even as questions persist on who is attending.