U.S. President Donald Trump’s special envoy Keith Kellogg said in Kyiv on Monday that officials are “working very, very hard” on efforts to end the three-year war between Russia and Ukraine, as a lack of progress fuels doubts about whether a peace settlement could be on the horizon.

Moscow continues to throw cold water on the prospect of Putin-Zelenskyy meeting, and is insisting Russia have a role in security guarantees for Ukraine.