Russian President Vladimir Putin will meet US special envoy Steve Witkoff in Moscow on Tuesday, after the White House said it was very optimistic about reaching a deal to end the Ukraine war.
US President Donald Trump's son-in-law Jared Kushner, who has acted as an outside adviser in diplomatic talks, is also expected to attend.
The summit comes after two days of negotiations in Florida between Ukrainian and US officials, including Witkoff and Kushner, aimed at refining a US-backed peace plan which had been viewed as favourable to Russia.
Ukrainian President Volodymyr Zelensky described the talks as constructive, but said there are some tough issues that still have to be worked through.
Speaking after a meeting with French President Emmanuel Macron in Paris on Monday, Zelensky said Kyiv's priorities in peace talks were maintaining Ukraine's sovereignty and securing strong security guarantees.
Zelensky said the territorial issue is the most difficult element of the peace deal, with the Kremlin continuing to push for Ukraine to cede territory in the east which it still controls - something Kyiv has long-maintained it will never do.
Witkoff also held talks with UK Prime Minister Sir Keir Starmer, Zelensky and Ukraine's new chief negotiator Rustem Umerov, while several key European leaders virtually joined the Zelensky-Macron meeting.
Speaking on Monday, White House Press Secretary Karoline Leavitt said the draft peace deal had been very much refined, adding: I think the administration feels very optimistic.
She continued: But as for the details, I will let the negotiators negotiate. But we do feel quite good, and we're hopeful that this war can finally come to an end.
Last week, Putin said he had seen a draft peace plan proposed by the US, and that it could become the basis for a future agreement to end the war.
However, Kremlin officials later cast doubt over whether it would accept the proposal after Kyiv and European allies said they had secured changes to it.
The initial US-Russia draft peace plan circulated in November sparked consternation in Kyiv and around Europe.
As well as being heavily slanted towards Moscow's demands, it also dictated how several billion in frozen Russian assets currently held in European financial institutions should be invested, as well as setting the terms for Ukrainian market access in Europe.
Speaking on Monday, Macron said there was currently no finalised peace plan to speak of, insisting that any proposal could only be worked out with input from Ukraine and Europe.
He emphasized that the question of territorial concessions could only be finalized by President Zelensky, pointing out that discussions around frozen Russian assets, security guarantees, and Ukraine's EU accession need to involve European nations.
The French leader praised efforts by the Trump administration to end the conflict, which began in 2014 with Russia's illegal annexation of Crimea, followed by a full-scale invasion of Ukraine in 2022.
Kaja Kallas, the EU's foreign policy chief, stated that this week could be pivotal, but noted that Moscow only wanted to negotiate with those who are just offering them something on top of what they already have.
She expressed concern that all pressure could fall on the weaker side, warning that such an outcome is not in anyone's interest.
The forthcoming talks in Moscow are further complicated by Russian claims of capturing strategic towns in eastern Ukraine, which Kyiv has not acknowledged. Open-source intelligence monitoring the front lines indicates these towns have not been firmly taken by the Russian army.
