The outgoing special envoy of U.S. President Donald Trump said that an agreement to end the war in Ukraine is “really very close,” noting that it now hinges on resolving two key outstanding issues: the future of Ukraine’s Donbas region and the Zaporizhzhia nuclear power plant.

Russia invaded Ukraine in February 2022 after eight years of conflict between Russian-backed separatists and the Ukrainian military in Donbas, which consists of the regions of Donetsk and Luhansk. The war in Ukraine is the bloodiest conflict in Europe since World War II and has triggered the greatest confrontation between Russia and the West since the Cold War.

U.S. Special Envoy for Ukraine Keith Kellogg, who is expected to leave his post in January, said at the Reagan National Defense Forum that efforts to resolve the conflict are in the “last 10 meters,” which, he noted, are always the most difficult. The two main unresolved issues, Kellogg added, concern territory — primarily the future of Donbas — and the future of Ukraine’s Zaporizhzhia nuclear power plant, the largest in Europe, currently under Russian control.

“If we settle these two issues, I believe the rest will go fairly well,” he said on Saturday at the Ronald Reagan Presidential Library and Museum in Simi Valley, California. “We’re close. We are really very close,” he added. Kellogg also described the scale of deaths and injuries caused by the war in Ukraine as “horrific” and unprecedented for a regional conflict.

He added that Russia and Ukraine have together suffered more than 2 million casualties — including both dead and wounded — since the war began. Neither Russia nor Ukraine publishes reliable casualty estimates, Reuters notes. Moscow claims Western and Ukrainian estimates of Russian losses are exaggerated, while Kyiv says Russia inflates its estimates of Ukrainian losses.

Russia currently controls 19.2% of Ukraine, including Crimea, which it annexed in 2014; all of Luhansk; more than 80% of Donetsk; about 75% of Kherson and Zaporizhzhia; and parts of the Kharkiv, Sumy, Mykolaiv, and Dnipropetrovsk regions, according to Reuters.

Last month, a leaked draft of a 28-point U.S. peace proposal caused concern among Ukrainian and European officials, who felt it conceded too much to Russia’s key demands regarding NATO, Moscow’s control of one-fifth of Ukraine, and limits on Ukraine’s military. According to the Kremlin, the proposals — now said to include 27 points — have been divided into four different sections. Their exact content has not been made public.

Under the initial U.S. proposals, the Zaporizhzhia nuclear power plant — currently non-operational — would resume operations under the supervision of the International Atomic Energy Agency, with the electricity it produces shared equally between Russia and Ukraine.

Ukrainian President Volodymyr Zelensky said on Saturday that he had a long and “substantive” phone call with the U.S. president’s special envoy, Steve Witkoff, and Donald Trump’s son-in-law, Jared Kushner. The Kremlin also announced on Friday that it expects Kushner to carry out most of the work needed to draft a possible agreement.