US offered Ukraine a 15-year security guarantee, Zelensky said after talks with Trump

Zelensky said the issue of giving up territory and the future of Ukraine's Moscow-occupied Zaporizhzhia nuclear power plant remain key unresolved points of the US-backed plan to end the war.

He added that he considered the presence of international troops in Ukraine a necessary part of any US guarantee, a proposition that Russia has rejected in the past.

Any deal to end Europe's worst conflict since WWII "must be signed by Ukraine, Russia, the US and Europe", he said.

Read moreLive: Putin hails Russian progress in 'liberating' Donbas, Zaporizhzhia and Kherson regions

Security guarantees have always been a priority for Kyiv.

"Without security guarantees, this war cannot be considered truly over. We cannot acknowledge that it has ended, because with such a neighbour there remains a risk of renewed aggression," Zelensky said.

He had told Trump the 15-year offer was too short a period for Kyiv.

"I told him that we really want to consider the possibility of 30, 40, 50 years," he added. "The president said he would think about it."

Details of the security guarantees have not become public but Zelensky said Monday that they include how a peace deal would be monitored as well as the “presence” of partners. He didn’t elaborate, but Russia has said it won’t accept the deployment in Ukraine of troops from NATO countries.

Kyiv was hoping for a meeting with European and American officials in Ukraine in the "coming days" to work on documents to end the conflict, Zelensky said.

'Strikes us with missiles' 

The Kremlin, for its part, agreed with Trump's assessment that peace talks were in their final stages but repeated its maximalist demand for Kyiv to withdraw from eastern Ukraine. Russian President Vladimir Putin called on Russian generals Monday to do what they needed to do to gain control of the city of Zaporizhzhia.

Russia continued its relentless attacks into the holiday season and pressed on with its demands in Ukraine.

WatchUkraine: What is blocking the peace deal negotiations?

Zelensky said that Kyiv was ready for "any" format of meetings – including with Putin if necessary – but said he still did not think the Kremlin chief wanted peace.

He accused Putin of misleading Trump.

"On the one hand, he tells the president of the United States that he wants to end the war and that this is his desire," Zelensky said. "And on the other hand ... he strikes us with missiles [and] gives instructions to his generals about where to advance."

Putin has for weeks told Russians that Moscow was intent on achieving its aims in Ukraine by force if diplomacy fails.

Moscow wants to keep all the territory it occupies in Ukraine as well as be handed lands in eastern Ukraine still controlled by Kyiv that Russia was unable to seize by force.

The Kremlin on Monday again called for Ukraine to withdraw from unoccupied parts of Donbas, warning that "Ukraine is losing territory and will continue to do so".

It said it expected Putin and Trump to speak by phone in the "very near future".

Territory issue unresolved

Trump on Sunday acknowledged the issue of territories were unresolved between the warring countries, showing little sign of a breakthrough.

"It's unresolved, but it's getting a lot closer. That's a very tough issue, but one that I think will get resolved," Trump said.

Zelensky also said it was a remaining issue and offered little detail, only saying:

"We will act in accordance with the interests of Ukraine."

The current plan, revised after weeks of intense US-Ukrainian negotiations, would stop the war at the current front lines in the eastern Donbas region and set up a demilitarised area, while Russia has long demanded territorial concessions.

But the Kremlin has shown no sign of compromise, with Putin repeatedly saying his troops will seize the rest of Ukrainian land he has proclaimed as historically Russian.

Outnumbered and exhausted Ukrainian troops have struggled to hold back a Russian advance, which has picked up pace since autumn.

Moscow on Monday said it took another village, Dibrova, in the Donetsk region.

(FRANCE 24 with AFP and AP)