"Militarily, Russia cannot be defeated, if we try, it will lead to a third world war, we cannot allow it," Gysi told German newspaper Spiegel.
Gysi noted that "Ukraine has the right to defense," but the parties should engage in negotiations.
"It [Ukraine] will not be able to win," Gysi added.
The Russian-Ukrainian negotiations began at the end of February when the delegations held meetings in Belarus. At the end of March, the delegations held another round of talks in Istanbul. Following the meeting, the Russian side announced that Ukraine had submitted its written proposals for a future peace treaty, which Moscow considered a step forward.
Later, the Russian Foreign Minister Sergey Lavrov said that Ukraine refused its own proposals and created numerous provocations in order to slow down the negotiation process.