Turkish President Recep Tayyip Erdoğan has had a telephone conversation with Russian leader Vladimir Putin, during which they discussed the possibility of holding a new round of negotiations between Ukraine and Russia in Istanbul.

Putin’s refusal to compromise on Ukraine, say analysts, is a colossal error costing Russia regional influence, lucrative energy markets and its place in the world.

The Kremlin said on Friday that it did not believe that a tougher stance U.S. President Donald Trump has adopted towards Russia over its war in Ukraine means the end of U.S-Russia talks aimed at reviving their battered ties.