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.

Just as their forces are stalemated on the battlefield, Russian President Vladimir Putin and Ukrainian President Volodymyr Zelensky are in a rhetorical standoff over preconditions for peace talks. Putin offered to begin talks Thursday in Istanbul under the auspices of Turkey with no preconditions,

U.S. and European officials held talks on May 12, during which Washington made it clear that it wanted to allow talks between Russia and Ukraine before increasing pressure on Vladimir Putin, sources told Bloomberg.