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.

U.S. President Donald Trump on Wednesday said he was still considering whether to attend talks on the war in Ukraine planned for Thursday in Turkey but he does not know whether Russian President Vladimir Putin will go.

President Volodymyr Zelensky of Ukraine said that if President Trump attended the talks, it would put pressure Russia’s leader, Vladimir V. Putin, to meet face-to-face.