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.

It’s been able to do so in part thanks to record oil and gas revenues, as it has filled a supply gap during the energy crisis triggered by Russia’s 2022 invasion of Ukraine. In 2022 alone, hydrocarbon sales generated roughly $150 billion for its national coffers,

President Donald Trump again expressed frustration with Russian counterpart Vladimir Putin as Russian strikes on Ukraine continued.