Russia proposed May 15 as the date for the Russian-Ukrainian talks in Istanbul, because Russian President Vladimir Putin decided so. This was stated by the press secretary of the head of state Dmitry Peskov to VGTRK journalist Pavel Zarubin.
"That's what the president decided," he said when asked about the choice of date.
Earlier, Russian Presidential aide Yuri Ushakov noted that the Russian side in Istanbul would discuss a "myriad" of political and technical issues, based on which its delegation from Moscow would be determined.