By Steve Holland ‌and Jeff Mason

WASHINGTON, Dec 15 (Reuters) - Ukraine could receive security guarantees modeled on NATO’s Article 5 mutual defense pledge under a proposed peace ‍deal with ‌Russia, U.S. officials said on Monday — an unprecedented offer aimed at ending the war sparked by Moscow’s 2022 invasion.

Officials described the proposed protections, ⁠discussed during two days of talks in Berlin, as “Article 5-like,” signaling ‌a strong commitment to Ukraine’s security even though Kyiv is not a NATO member.

Two officials, speaking to reporters on a conference call after U.S. peace talks with Ukrainian and European officials, said the guarantees would not be on the table forever, as U.S. President Donald Trump presses for an end to the war sparked by Russia's ⁠2022 full-scale invasion of Ukraine.

The officials said there was broad agreement on 90% of the issues between Ukraine and Russia. But they acknowledged that territory and sovereignty would still have ​to be resolved by the parties themselves. Ukraine has said previously it would not cede ‌territory to Russia.

Opinion polls in Ukraine have shown that few Ukrainians ⁠are willing to accept territorial concessions, which remains a key Russian condition for ending its war. 

The Russians have shown little willingness to compromise on their demands. 

One U.S. official said Russia was open to Ukraine joining the European Union and that Trump wanted to prevent Russia from ​moving further west. 

Article 5 is considered the cornerstone of the NATO defense alliance's founding treaty. It stipulates that an attack against one member of the group is considered an attack against them all.

It was unclear how far the United States would go in providing such security guarantees to Ukraine. The officials said the guarantees would include intense monitoring and deconfliction measures to prevent small conflicts from becoming larger ones.

"Those guarantees will not ​be on ‍the table forever. Those guarantees are on the ​table right now if there's a conclusion that's reached in a good way," one official said.

The talks in Berlin were led on the U.S. side by Trump envoys Steve Witkoff and Jared Kushner, the president's son-in-law.

The officials said longstanding territorial issues remain but one said, "We've got multiple different solutions to bridge the gap that we are suggesting to them."

Witkoff and Kushner were attending a dinner on Monday night in Berlin with the other negotiators and Trump was expected to call into the event, the officials said.

Working groups are expected to meet in the United States during the coming weekend, ⁠possibly in Miami, one of the officials said.

"I think you're going to hear that we have moved considerably closer in narrowing the issues between the Ukrainians and the Russians. That's clear," the official said.

The official said ​a working group came up with a three-page draft on territory issues and Zelenskiy is expected to discuss it with his team, and the U.S. side will eventually discuss the topic with the Russians.

The officials described the security guarantees as "Article 5-like" in categories such as oversight and deconfliction.

Negotiators also discussed what one U.S. official described as a "prosperity package" to help Ukraine rebuild. BlackRock CEO Larry ‌Fink has formed a team to work on the issue with the World Bank, and European officials indicated a willingness to provide financial support for it, the official said.

(Reporting by Steve Holland and Jeff Mason; additional reporting by Costas Pitas, Editing by Franklin Paul, Chizu Nomiyama and Howard Goller)