President Volodymyr Zelensky said on Friday that Ukraine faced losing its dignity and freedom or Washington's support over a US peace plan which endorses key Russian demands, a plan that Donald Trump said Kyiv should agree to by Thursday.

Trump told Fox News Radio he believed next Thursday was an appropriate deadline for Kyiv to accept the plan, confirming what two sources had told Reuters.

In a solemn address delivered on the street outside his office, a location he uses only rarely for major addresses, Zelensky appealed to Ukrainians for unity and said he would never betray Ukraine.

'A very difficult choice'

"Now is one of the most difficult moments of our history. Now, the pressure on Ukraine is one of the heaviest. Now, Ukraine can face a very difficult choice — either losing dignity or risk losing a major partner," he said.

"I will fight 24/7 to ensure that at least two points in the plan are not overlooked – the dignity and freedom of Ukrainians," Zelensky said.

Washington has presented Kyiv with a 28-point plan, which calls for Ukraine to cede territory, accept limits to its military, and renounce ambitions to join NATO.

The United States threatened to cut off intelligence sharing and weapons supplies for Ukraine if it does not accept the deal, two sources said, speaking on condition of anonymity.

The White House did not immediately respond to a request for comment. A senior US official later said it was not accurate to say the US threatened to withhold intelligence.

A US military delegation met Zelensky in Kyiv on Thursday. The US ambassador and the army public affairs chief travelling with the delegation described the meeting as a success and said Washington sought an "aggressive timeline" for the US and Ukraine to sign a document.

'A real and dignified peace'

Zelensky held a phone call on Friday with the leaders of Britain, Germany, and France, and later spoke to US Vice President JD Vance. He said he had agreed with Vance to work at adviser level "to find a workable path to peace".

Three sources later told Reuters that Ukraine was working on a counter-proposal to the 28-point plan with Britain, France, and Germany. The Europeans have not been consulted on the US plan and have expressed strong support for Kyiv.

In earlier remarks, Zelensky appeared careful not to reject the US plan or offend the Americans.

"We value the efforts of the United States, President Trump, and his team aimed at ending this war. We are working on the document prepared by the American side. This must be a plan that ensures a real and dignified peace," he said.

But the plan's call for terms that Kyiv has rejected in the past as capitulation could test the stability of Ukrainian society after nearly four years of relentless warfare.

"Russia gets everything it wants and Ukraine gets not very much. If Zelensky accepts this I anticipate huge political, social and economic instability in Ukraine," said Tim Ash of Britain's Chatham House think tank.

'A very dangerous moment'

European leaders expressed their strong support for Kyiv.

"We all want this war to end, but how it ends matters. Russia has no legal right whatsoever to any concessions from the country it invaded," said the EU foreign policy chief, Kaja Kallas. "This is a very dangerous moment for all."

US officials, defending their plan, said it was drafted after consultations with Rustem Umerov, secretary of Ukraine's National Security and Defense Council, a close Zelensky ally who served as defence minister until July.

Umerov "agreed to the majority of the plan, after making several modifications, and presented it to President Zelensky," a senior US official said on Thursday.

Umerov denied agreeing to any of the plan's terms, and said he had played only a technical role organising talks: "This is not within my authority and does not correspond to the procedure," he wrote on Telegram.

The Kremlin said Russia had not received anything official from the United States about a peace plan. Kyiv should make a "responsible decision", and do it now, Kremlin spokesman Dmitry Peskov said.

Russia's demands spelled out, Kyiv's left vague

The plan, a copy of which was reviewed by Reuters, would require Ukraine to withdraw from territory it still controls in eastern provinces Russia claims to have annexed, while Russia would give up smaller amounts of land it holds in other regions.

Ukraine would be permanently barred from joining NATO, and its armed forces would be capped at 600,000 troops. NATO would agree never to station troops there.

Sanctions against Russia would be gradually lifted, Moscow would be invited back into the G8 group of industrialised countries, and frozen Russian assets would be pooled in an investment fund, with Washington receiving some of the profits.

One of Ukraine's main demands, for enforceable guarantees equivalent to the NATO alliance's mutual defence clause to deter Russia from attacking again, is dealt with in a single line with no details: "Ukraine will receive robust security guarantees".

Trump has accepted some of Russia's justifications for its 2022 invasion of its neighbour while also expressing impatience with Moscow.

Last month he cancelled a proposed summit with Russia's Vladimir Putin and imposed sanctions on Russia's two main oil companies, set to come into full effect on Friday, Washington's deadline for foreign buyers to wind down Russian oil purchases.

Trump said on Friday he expected the "powerful" sanctions to have their intended effect on Russia, adding: "Their whole economy is based on oil". He said he would not remove the sanctions before implementation of the 28-point plan.