US special envoy Steve Witkoff and Ukraine's Volodymyr Zelensky are due to meet in Oslo, with relations on the slide between the Ukrainian leader and US President Donald Trump.
Norwegian Prime Minister Jonas Gahr Støre said Zelensky had asked Oslo and neighbouring Finland to organise the meeting with the US and European allies "at a critical time for Ukraine".
Ahead of the meeting, US Secretary of State Marco Rubio rejected as "scandalous" and "outrageous" accusations that Ukrainians were dying because the US was withholding intelligence from Kyiv.
He was speaking after Zelensky's military technical adviser, Serhii "Flash" Beskrestnov, told the BBC that the lack of reliable US warnings meant lives were being lost.
"This looks very strange," said Beskrestnov. "Sometimes we receive this information before the attack, another time we [do] not."
Relations between Kyiv and the US have soured in recent weeks to the extent that Trump has said it is time for Ukraine to get a new president, and most recently "for somebody else to negotiate on behalf of Ukraine".
Zelensky first met the Norwegian prime minister and Finnish President Alexander Stubb, ahead of his planned talks in person with Witkoff, with Trump's son-in-law Jared Kushner taking part via video link.
Støre said the aim of the Oslo talks was to steer relations towards "a more constructive path". He told reporters at the parliament in Norway that they wanted to ensure that the war ended diplomatically with a lasting and just peace.
The Ukrainian leader said earlier he had had a "constructive discussion" with Rubio about the need for US early warnings, missile interceptors and SpaceX's Starlink internet network.
Last week a bipartisan group of US senators called for an urgent investigation into disruptions to the Starlink network in Ukraine, and unconfirmed reports on Tuesday said the transfer of more Patriot interceptors had not yet been approved.
The US secretary of state is currently on a visit to India and admitted to reporters that it may be true that Patriot interceptor missiles had not yet arrived in Ukraine, although nothing had been denied to Kyiv intentionally.
Zelensky was set to join his Norwegian and Finnish counterparts for a press conference after the talks, but Witkoff was not expected to join them, according to the government in Oslo.
It is not yet clear whether Witkoff will travel on to Russia after his visit to Oslo, however the Kremlin spokesman said he hoped a meeting with Trump's special envoy could be organised in the near future. Dmitry Peskov said "we greatly appreciate the mediation efforts of the American negotiators".
Earlier this month Russia's Vladimir Putin discussed the war with Trump over the phone, and afterwards the US president announced that Moscow would immediately supply more than 300,000 tons of diesel to the US and other markets, bringing to an end American sanctions on Russian diesel exports.
Trump's deal with the Russian leader coincided with Witkoff and Kushner's last meeting with Ukrainian officials in Miami, and Zelensky reacted by calling it "a happy birthday present for Putin".
Ahead of next month's US midterm elections, Trump has blamed Ukraine's attacks on Russian oil refineries for fuel prices which have reached record highs at the pump since the start of the US-led war on Iran.
European leaders have expressed concern about recent statements from the US towards Russia, and German Chancellor Friedrich Merz spoke on Monday of "mixed pictures and messages" on the war, adding that he was trying to convince the American government "in total that this is something we have to resolve jointly".
He pointed out that the US had not been paying for the defence of Ukraine since the start of 2025, and Europe and other countries were shouldering the burden.
"It's really a big effort for our budgets, it's really a big thing for the European Union, but we are doing that and we are trying to keep on doing that until this terrible war ends," the German leader told Bloomberg TV.
Asked whether or not Ukraine was a US ally, Vice-President JD Vance has said in a TV interview that Kyiv was "certainly a partner in some ways, but we have some divergent interests from time to time, like for example... I think they should stop bombing Russian energy".
"We don't have a formal alliance as far as I know with Ukraine. They're not in Nato, I don't think they should be in Nato... we're gonna work together on some things, but also we're going to be opposite on some things too."
