Meeting NATO partners the day after President Donald Trump revealed he plans to start peace talks with Russia's Vladimir Putin, Pentagon chief Pete Hegseth denied it meant a betrayal of Kyiv's three-year war effort.

But Trump's move stunned Ukraine and European allies -- several of whom openly called his strategy into question.

Zelensky said it was "not very pleasant" that Trump had called Putin first before speaking to him, adding the US president had said he wanted to speak to both leaders together.

The Ukrainian leader -- who is set to meet US Vice President JD Vance in Munich on Friday -- said he wanted to hammer out a "plan to stop Putin" with the United States before any talks happen.

After a 90-minute phone call with Putin on Wednesday, Trump's first since returning to power, the US president said he expected to meet the Russian leader in Saudi Arabia for Ukraine peace talks -- sparking fears Kyiv would be frozen out.

The Kremlin -- which wants broader European security should be on the agenda -- said that "one way or another" Kyiv would be involved in the talks, but there would also be a "bilateral Russian-American track".

Ukraine's European backers rejected any move to force a settlement on Kyiv and criticised Washington's apparent willingness to give all its cards to Moscow.

German Chancellor Olaf Scholz rejected any "dictated peace" and his defence minister called it "regrettable" that Washington was already making "concessions" to the Kremlin.

In a blunt address to reporters at NATO talks in Brussels, EU top diplomat Kaja Kallas insisted that no deal "behind our backs" could work, as she accused Washington of "appeasement" towards Russia.

"We shouldn't take anything off the table before the negotiations have even started because it plays to Russia's court and it is what they want," she said.

"Any quick fix is a dirty deal," she said. "It will just simply not work."

That came after Trump's administration poured cold water on Ukraine's goals of reclaiming all its territory and pushing to join NATO.

Hegseth said Europe must now start providing the "overwhelming share" of aid to Ukraine and that the United States would not deploy troops as a security guarantee under any deal.

"There is no betrayal there. There is a recognition that the whole world and the United States is invested and interested in peace," the Pentagon chief said at NATO.

"That will require both sides recognising things they don't want to."

He denied that Trump had already given up leverage to Putin, and said that negotiations would involve both the Russian leader and Zelensky.

Ukraine's defence minister Rustem Umerov told Kyiv's NATO backers "we're continuing, we're strong, we're capable, we're able, we will deliver".

Zelensky's meeting with Vance in Munich will be the latest in a flurry of high-level European encounters for top Trump officials.

US Treasury Secretary Scott Bessent held talks in Kyiv on Wednesday on granting Washington access to Ukraine's rare earth deposits in return for security support.

- Losses in Kursk -

Trump's outreach to Putin had been broadly expected, but the quick pace of his peace push has left heads spinning after three years of staunch Western support for Kyiv.

Kyiv's European backers are terrified that Trump could force Ukraine into a bad peace deal that will leave them facing an emboldened Putin -- while fronting the lion's share of costs for post-war security.

Antonio Costa, who heads the European Council representing the EU's 27 nations, warned against settling for a deal that did not neutralise Russia's threat to Europe.

"Peace cannot be a simple ceasefire. Russia must no longer be a threat to Ukraine, to Europe, to international security," he said.

Hegseth said that European troops could provide the security guarantees for Ukraine under a deal -- and his British counterpart John Healey said planning was "accelerating" on that front.

Zelensky has raised the possibility of swapping Russian territory held by Kyiv for Ukrainian land Moscow occupies

But Ukraine's grip on Russia's Kursk region has slipped -- with Kyiv saying it now holds barely a third of the area it captured last year.