Turkish President Recep Tayyip Erdogan (R) shakes hands with his Ukrainian counterpart Volodymyr Zelensky during a welcoming ceremony at the Presidential Palace in Ankara, Turkey, on Aug. 7, 2019. (Photos: Mustafa Kaya/Xinhua)

Turkish President Recep Tayyip Erdogan (R) and his Ukrainian counterpart Volodymyr Zelensky attend a press conference at the Presidential Palace in Ankara, Turkey, on Aug. 7, 2019.

Turkish President Recep Tayyip Erdogan (R) and his Ukrainian counterpart Volodymyr Zelensky attend a press conference at the Presidential Palace in Ankara, Turkey, on Aug. 7, 2019.

Turkish President Recep Tayyip Erdogan (L, front) and his Ukrainian counterpart Volodymyr Zelensky (R, front) review the guard of honor during a welcoming ceremony at the Presidential Palace in Ankara, Turkey, on Aug. 7, 2019.