Russia, the US and Ukraine agree that a deal on ending almost four years of full-scale war is edging closer but, in the words of President Donald Trump, "one or two very thorny, very tough issues" remain, BBC reported. 

Two of the trickiest issues in Washington's 20-point plan involve territory and the fate of Europe's biggest nuclear plant, which is currently occupied by Russia.

The Kremlin agrees with Trump that negotiations are "at a final stage", and Zelensky's next step is to meet European leaders in France on 6 January, but any one of the sticking points could jeopardise a deal, according to BBC.