US Defense Secretary Pete Hegseth has said that a return to Ukraine's pre-2014 borders was unrealistic and the Trump administration does not see NATO membership for Ukraine as part of a solution to the war triggered by Russia's invasion.
Speaking at a meeting of Ukraine's military allies at NATO headquarters in Brussels, Mr Hegseth delivered the clearest and bluntest public statement so far on the new US administration's approach to the nearly three-year war.
He also told Washington's NATO allies that they would have to step up and assume greater responsibility for Europe's security.
"We want, like you, a sovereign and prosperous Ukraine. But we must start by recognising that returning to Ukraine'spre-2014 borders is an unrealistic objective," Mr Hegseth told the meeting of more than 40 countries allied to Ukraine.
"Chasing this illusionary goal will only prolong the war and cause more suffering," he added.
Russia annexed the Black Sea peninsula of Crimea from Ukraine in March 2014 and then backed pro-Russian separatists in an armed insurgency against Kyiv's forces in the eastern Donbas region of Ukraine.
Russia currently controls about 20% of Ukraine's territory, mainly in the east and south.
Mr Hegseth said any durable peace must include "robust security guarantees to ensure that the war will not begin again".
But, he said, "the United States does not believe that NATO membership for Ukraine is a realistic outcome of a negotiated settlement".
Instead, security guarantees should be backed by "capable European and non-European troops", the Pentagon chief said.
"If these troops are deployed as peacekeepers to Ukraine at any point, they should be deployed as part of a non-NATO mission and they should not be covered under Article 5," he said, referring to the alliance's mutual defence clause.
In a forceful introduction at NATO headquarters, the former television anchor set out the contours for a future deal that Mr Trump has vowed to reach on ending Russia's war on Ukraine.
"Our message is clear, the bloodshed must stop and this war must end," he told a group of Kyiv's backers that included his Ukrainian counterpart.
Mr Hegseth said that Mr Trump was "unleashing US energy production" and urging other producers to do so in a bid to drive down prices - and push Moscow to negotiate.
But he insisted that Europe must now start providing the "overwhelming share" of aid to Ukraine.
The tough US stance had largely been expected but it will still provide a cold shower for Kyiv as its forces struggle to hold back Russia.
Mr Hegseth's visit to NATO headquarters is part of the first flurry of high-ranking American visits to Europe since Trump took power.
Those are set to culminate with Vice President JD Vance meeting Ukraine's leader Volodymyr Zelensky in Munich on Friday.
On European security, Mr Hegseth echoed Mr Trump's demands for NATO to more than double its defence spending target to 5% of GDP.
While he said Washington remained committed to NATO, the United States will "no longer tolerate an imbalanced relationship" that sees Europe underpaying.
He warned that US prime interests were focused on the threat from China and that there may be "trade offs" on American involvement in Europe.
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"As the United States prioritises its attention to these threats, European allies must lead from the front," he said.
US allies have already stepped up their spending in the face of Russia's invasion of Ukraine and are pledging to do more to back Kyiv.
"Secretary Hegseth, we hear you," said Britain's defence minister John Healey in a brief response.
"We hear your concerns on stepping up for Ukraine, we are and we will. On stepping up for European security. We are and we will."
Britain announced a fresh package of aid for Ukraine worth $185 million.
NATO's European members are terrified about Ukraine being forced into a bad deal that lets Moscow claim victory and leave them facing the threat of an emboldened Russia.
The United States has underpinned European security through NATO over the past seven decades.
Mr Hegseth's broadside is set to fire a starting pistol on negotiations for setting a new spending target for alliance members at a June summit in the Netherlands.
NATO chief Mark Rutte said he expects the goal to be raised to "north of 3%".
"We need to do a lot more so we have what we need to deter and defend. And so that there is more equitable burden sharing," he said.
