European leaders are adamant that any plan to end Russia’s war in Ukraine will need support from both the European Union and Ukraine amid speculation of a potential United States-backed plan that would heavily favour Moscow’s demands and narrative.

Arriving for a meeting of EU foreign ministers in Brussels on Thursday, EU foreign policy head Kaja Kallas told reporters that Europeans have always supported “long-lasting and just peace, and we welcome any efforts to achieve that”.

“Of course, for any plan to work, it needs Ukrainians and Europeans on board,” she added.

Other top diplomats from Germany, Spain and Poland echoed Kallas, with Polish Foreign Minister Radoslaw Sikorski saying that Europe – whose security is “at stake” – expects to be consulted on any potential deal.

“I hope it’s not the victim that has restrictions on its ability to defend itself put on, but it’s the aggressor,” he said.

Russia, however, appeared to push off the idea of negotiations, saying again on Thursday that a deal with Ukraine would have to eliminate the root causes of the conflict and that there are no negotiations ongoing with Washington on such a plan.

Kremlin spokesman Dmitry Peskov declined to comment on whether Russian President Vladimir Putin had been briefed on the details of the reported Ukraine peace plan, Reuters news agency reported.

European nations have been increasingly concerned that the war may spill into their borders, and there have been numerous accusations and instances of the Kremlin undertaking actions of shadow war, testing the EU and the United Kingdom’s mettle with aggressive cyberattacks and drone intrusions.

The UK on Wednesday warned it is ready to use “military options” if necessary after a Russian spy ship that has spent weeks on the edge of British waters directed lasers at British pilots sent to monitor the vessel.

Word of the US proposal came as a deadly wave of Russian attacks killed at least 26 people in Ukraine’s city of Ternopil on Wednesday, including three children.

Another 22 people were still missing as of Thursday morning, Ukrainian President Volodymyr Zelenskyy wrote on X, with more than 230 first responders deployed in search and rescue efforts.

“Once again, the Russians have killed innocent, peaceful people who were simply sleeping in their homes,” the president said.

Ukrainian Prime Minister Yulia Svyrydenko separately welcomed Secretary of the US Army Daniel Driscoll to Ukraine on Thursday, writing on X that the visit was “an important opportunity for the senior military officials accompanying the secretary to assess the situation on the ground and to witness firsthand the consequences of Russian aggression”.

News reports released on Wednesday, quoting unnamed officials, meanwhile, said the US proposal was created in consultation with Russian officials and closely hews to Russia’s vision for ending the war.

The Financial Times reported the 28-point plan was delivered by US envoy Steve Witkoff in a meeting with Rustem Umerov, secretary of Ukraine’s National Security and Defence Council, in Miami, Florida, in the US earlier this week.

It would require Ukraine to give up the rest of the eastern region of Donbas – long eyed by Russia for its industrial history and strategic location, and where fierce fighting rages – including territory under Kyiv’s control. The proposal would also demand cuts to Ukraine’s military, several outlets reported.

Ukraine’s Zelenskyy – who sparred with US President Donald Trump and Vice President JD Vance in a dramatic meeting in February – has been clear since Russia’s 2022 invasion that potential peace talks ought not sideline Ukraine, a viewpoint shared by much of the EU’s leadership.

“We, as a sovereign country, simply will not be able to accept any agreements without us,” Zelenskyy said ahead of that contentious meeting.

He has since repeatedly made clear several red lines that neither the Ukrainian government nor its constitution would permit, including ceding its territory.

Still, some European leaders have offered less enthusiasm. Hungary’s Foreign Minister Peter Szijjarto said the EU should stop sending money to Ukraine in seeming reference to an ongoing corruption probe involving an alleged $100m energy kickback scheme.

Last week, Ukraine’s Justice Minister German Galushchenko and Energy Minister Svitlana Hrynchuk submitted their resignations as anticorruption authorities said they had detained five people suspected of an alleged plot to control procurement at nuclear agency Energoatom.

“There’s a war mafia, a corrupt system working in Ukraine, and then the European Commission president … instead of stopping the payments and demanding for immediate financial clearance, she wants to send another 100 billion to Ukraine. That is insane,” Szijjarto said.

Hungary’s right-wing populist leader Victor Orban, who counts Russian Putin as an ally, has been blocking Ukraine’s EU bid, received an exemption on Russian energy sanctions from Trump and a “financial shield” to safeguard its economy in recent weeks.

“The time is not on the side of Ukraine. It is an illusion to say that the time is on the side of Ukraine,” Szijjarto said, adding that he would support Trump’s peace initiatives.