U.S. President Donald Trump and his Russian counterpart Vladimir Putin were still "maybes" for what could be the first direct peace talks between Moscow and Kyiv in years after the Kremlin on Wednesday held off disclosing who would represent Russia.

Russian President Vladimir Putin in the early hours of Sunday proposed direct negotiations in Turkey on Thursday "without any preconditions," but he did not say who would attend from Moscow's side. Ukrainian President Volodymyr Zelenskiy has said he would attend the talks with Russia only if Putin is also there.

Russia resumed mass drone attacks in Ukraine early on Sunday, after its self-declared three-day pause expired.