Ukrainian President Volodymyr Zelenskyy on Tuesday said his country needs to convince U.S. President Donald Trump that Vladimir Putin is not a trustworthy partner as he urged the Russian president to show up for peace negotiations in Turkey later this week.

“Trump needs to believe that Putin actually lies,” Zelenskyy told a group of reporters in Kyiv, according to The Guardian. “And we should do our part. Sensibly approach this issue, to show that it’s not us that is slowing down the process.”