KYIV, Ukraine (AP) — 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.

Russian Foreign Minister Sergey Lavrov made the declaration in an interview with NBC’s “Meet the Press,” suggesting that Putin will not be able to make an agreement with him.

Russian president Vladimir Putin is reportedly willing to freeze current front lines in exchange for Ukrainian territorial concessions and a NATO membership ban.