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.

President Donald Trump announced Tuesday he is sending Secretary of State Marco Rubio to attend peace talks between Russia and Ukraine in Turkey later this week. Speaking from Saudi Arabia, Trump said Rubio would be going to the talks and suggested other administration officials would be present as well.