Russia has so far refused to agree to a face-to-face meeting between Zelensky and Putin, despite several requests from Kyiv. The Kremlin hasn't ruled out summits for the two leaders but has said they could only meet in the very final stages of clinching a peace agreement.

"How can we meet with a person who is pretending to be a leader?" Russian Foreign Minister Sergey Lavrov told NBC News on Aug. 22.

Ukrainian President Volodymyr Zelensky said he is ready to make “some compromise” on his demand that a ceasefire takes place before any talks with Russian President Vladimir Putin – as long as some security guarantees for Ukraine are established.