In an interview with pro-Trump journalist Tucker Carlson, Witkoff praised Vladimir Putin, saying he "liked" the Russian president.
"I don't regard Putin as a bad guy," he said. "He's super smart."
Witkoff, who met Putin 10 days ago, said the Russian president had been "gracious" and "straight up" with him. Putin told him, he added, that he had prayed for Trump after an assassination attempt against him last year. He also said Putin had commissioned a portrait of the US president as a gift and Trump was "clearly touched by it".
During the interview, Witkoff repeated various Russian arguments, including that Ukraine was "a false country" and asked when the world would recognise occupied Ukrainian territory as Russian.
Witkoff is leading the US ceasefire negotiations with both Russia and Ukraine but he was unable to name the five regions of Ukraine either annexed or partially occupied by Russian forces.
He said: "The largest issue in that conflict are these so-called four regions, Donbas, Crimea, you know the names and there are two others."
The five regions - or oblasts - are Luhansk, Donetsk, Zaporizhzhia, Kherson and Crimea. Donbas refers to an industrial region in the east that includes much of Luhansk and Donetsk.
Witkoff made several assertions that are either not true or disputed:
- He said Ukrainian troops in Kursk were surrounded, something denied by Ukraine's government and uncorroborated by any open-source data
- He said the four partially occupied regions of Ukraine had held "referendums where the overwhelming majority of the people have indicated that they want to be under Russian rule". There were referendums only in some of the occupied parts of Ukraine at different times and the methodology and results were widely discredited and disputed
- He said the four partially occupied oblasts were Russian-speaking. There are many Russian-speaking parts of Ukraine but this has never indicated support for Russia.