Negotiators from the United States, Ukraine and Russia were meeting behind closed doors in Abu Dhabi, US and British media reported.
The White House cited “tremendous progress,” while cautioning “there are a few delicate but not insurmountable details that must be sorted out.”
This “will require further talks between Ukraine, Russia, and the United States,” White House Press Secretary Karoline Leavitt posted on X.
US negotiator Dan Driscoll emerged upbeat from meeting with Russian counterparts, his spokesman saying: “The talks are going well and we remain optimistic.”
Frantic discussions have been underway since the weekend when Ukrainian and US representatives huddled in Geneva on a controversial 28-point plan from President Donald Trump that heavily favored Russian war demands.
The war, which began with Russia’s full-scale invasion of Ukraine in 2022, continued unabated.
Powerful explosions rocked Kyiv beginning around 1:00 am (2300 GMT), as Russian drones and missiles rained down, setting fires in apartment buildings. City officials said seven people were killed.
Thick smoke, turning red and orange in the blizzard of Ukrainian air defense fire, rose over the capital as residents fled underground into metro stations, AFP reporters said.
Ukrainian Foreign Minister Andriy Sybiga called the barrage Russian President Vladimir Putin’s “terrorist response” to the negotiations.
Russia fired 464 drones and 22 missiles overnight, Ukraine’s air force said, while Ukraine fired almost 250 of its own drones at Russia, according to Russian authorities.
Three people were killed in the southern Russian border region of Rostov, authorities said, with the governor of nearby Krasnodar calling it one of the “most sustained and massive attacks” of the war.