Ukrainian President Volodymyr Zelensky (R) and German Chancellor Angela Merkel attend Normandy Four Summit in Paris, France, Dec. 9, 2019. Ukraine and Russia agreed on a full and comprehensive implementation of the ceasefire in eastern Ukraine before the end of 2019, leaders of Russia, Ukraine, France and Germany announced in Paris on Monday evening following their talks called Normandy Four Summit. (Xinhua/Gao Jing)