US President Donald Trump said that Sunday's meeting with Ukrainian President Volodymyr Zelensky was "terrific", though he admitted there were still "thorny issues" that stood in the way of a peace deal in the deadliest conflict in Europe since World War II.

Few details were available after the meeting at Mar-a-Lago, Trump's private club in Palm Beach, Florida, but the US president told a news conference afterward that "we made a lot of progress today".

Zelensky said that "great achievements" had been made, adding that security guarantees were close to being agreed upon between the US, Europe and Ukraine.

"We agreed that a security guarantee is the key milestone in achieving lasting peace, and our teams will continue working on all aspects," Zelensky said after the meeting.

Sunday's meeting marked the fifth time Zelensky had met Trump in the US.

"We discussed all the aspects of the peace framework," Zelensky said, adding that about 90 percent the peace plan had been agreed to.

Trump said that before meeting Zelensky he'd had a "good and very productive" call with Russian President Vladimir Putin.

Kremlin spokesperson Yury Ushakov said Trump and Putin had a "broadly similar view" during their call that a temporary ceasefire would "prolong the conflict", and urged Ukraine to decide on the Donbas region "without delay".

Issues such as the Donbas region and the Zaporizhzhia nuclear power plant remain unresolved.

Putin has said he wants to keep the areas that have been captured in four key regions, as well as the Crimean Peninsula, and has insisted that Ukraine abandon its bid to join NATO, warning that Russia wouldn't accept the deployment of any NATO troops in Ukraine.

In the past few weeks, competing draft peace proposals have been announced — including a 28-point plan believed to originate in Moscow and a 20-point plan from Kyiv.

"Ukraine is willing to do whatever it takes to stop this war," Zelensky posted on Saturday on X. "We need to be strong at the negotiating table."

The United States recently said it would offer security guarantees to Ukraine similar to those offered to NATO members. Zelensky has said he would drop a bid by Ukraine to join the alliance if Ukraine received similar NATO-like protection.

When asked about security guarantees before the meeting, Trump responded: "There will be a security agreement. It will be a strong agreement. The European nations are very much involved in that."

On Christmas Day, Zelensky also spoke with US special envoy Steve Witkoff and Trump's son-in-law Jared Kushner. Zelensky said they had discussed "certain substantive details", though cautioning in a post on X that "there is still work to be done on sensitive issues" and "the weeks ahead may also be intensive."

The US delegation on Sunday included Secretary of State Marco Rubio and Defense Secretary Pete Hegseth, while Economy Minister Oleksii Sobolev was present for the Ukrainians.

Trump said much of the progress achieved on Sunday had made been made over the last month.

"This is not a one-day process deal. This is very complicated stuff," Trump said at the news conference. "Russia would like to see it end, and Ukraine would like to see it end, and I think it's time to end," Trump said.