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.

Ukraine launched a large drone strike Sunday that caused damage at Russia's Kursk Nuclear Power Plant and a major fuel export terminal hundreds of miles away.