He added that Kyiv needed a “clear understanding of security guarantees” before it could make any decisions about other contentious issues.
Ukraine has long argued it needs watertight guarantees to ensure that Russia respects any ceasefire and does not attack the country again.
US officials described the security guarantees on offer as the “platinum standard”, but cautioned the deal “would not be on the table forever”.
On Sunday, Zelensky signalled for the first time that as a “compromise” he would give up ambitions to join Nato in exchange for strong guarantees.
While there appears to be significant movement on the issue of security, the eastern region of the Donbas remains a major sticking point.
The US is now suggesting an “economic-free zone” could be established in the contested part of the Donbas, but that would require Ukraine accepting to withdraw from the areas it still holds, while Russia would not be expected to do the same.
“It seems to me that [the US and Ukraine] so far have different positions, to be honest,” Zelensky said.
US officials said that if the economic free zone could be defined, “then it will really be up to the parties to work out the final issues of sovereignty.”
But Moscow and Kyiv remain far apart on the issue of the Donbas. Russia mostly occupies the region and it wants Kyiv to hand it over in its entirety, which Ukraine is staunchly refusing to do.
The US officials said Washington was now willing to submit a security package for Senate ratification.
Several European leaders, as well as European Commission President Ursula von der Leyen, will join further talks with the Ukrainian and US delegations on Monday evening. President Donald Trump was likely to call into the meeting, US officials said.
German Chancellor Friedrich Merz, who hosted the discussions, said the US had put forward “remarkable” security guarantees.
“It’s a huge progress which I welcome very much,” he added. “This is the first time a ceasefire is conceivable.”
