Ukraine was plunged into gloom and uncertainty after Donald Trump’s victory amid expectations that he is likely to end US military assistance while the Kremlin said its aim of subjugating its neighbour remains unchanged.

Volodymyr Zelenskyy, Ukraine’s president, congratulated Trump on his “impressive election victory”, adding: “I appreciate President Trump’s commitment to the ‘peace through strength’ approach in global affairs.”

He recalled their “great meeting” in New York in September and said the two had discussed “ways to put an end to Russian aggression in Ukraine”. He praised Trump’s “decisive leadership” and cited the “strong bipartisan support for Ukraine” in the US.

The consequences for Ukraine of Trump’s second presidency are likely to be difficult, however, at a time when Russia is already advancing on the battlefield at the quickest rate since 2022.

Without US military assistance, Ukraine stands to lose further ground in Donetsk oblast, the scene of fierce fighting since Vladimir Putin’s full-scale invasion nearly three years ago, as well as in many other frontline areas.

Russia’s foreign ministry said Moscow would seek to work with a future Trump administration, but added that it was “focusing on achieving all the set objectives of the special military operation” – the Kremlin’s term for the war. “Our conditions are unchanged and are well known in Washington,” it added.

Dmitry Peskov, the Kremlin spokesperson, said he was not aware of any plans by Putin to call and congratulate Trump on his victory. Any reset of policy between Russia and the US would take some time, he added.

“We have repeatedly said that the US is able to contribute to the end of this conflict. This cannot be done overnight, but … the US is capable of changing the trajectory of its foreign policy,” Peskov told a daily briefing of reporters.

Trump once boasted he could end the decade-long Russo-Ukrainian war in “24 hours”. His future vice-president, JD Vance, is an outspoken Kyiv sceptic who has said he “does not really care what happens to Ukraine, one way or another”.

Zelenskyy has, however, become increasingly frustrated with Joe Biden’s administration. The outgoing US president has batted away Ukraine’s longstanding request for permission to use western long-range weapons against military targets deep inside Russia.

Orysia Lutsevych, the head of the Ukraine forum at the Chatham House thinktank, said she feared Trump’s election could be “a gift to the Kremlin” if Zelenskyy could not make Trump buy into his vision, but too said there considerable frustration in Kyiv at “Biden’s incrementalism” and a hope that “things could shift in favour of Ukraine” because Trump might suddenly pursue a more interventionist policy.

Ukrainians in Kyiv’s city centre offered a range of views. Andriy, 30, a combat engineer, on training leave in the city after a spell in the frontline near the town of Niu York, said he was not sure a Trump presidency would make much difference because “our brigade has not seen any American weapons”.

The country had little choice but to fight on with or without US help, the soldier said, because “if we don’t we will be destroyed, literally erased” by the Russian invaders. Oksana, 53, who said friends of hers had been killed in the fighting, called on for greater help from Europe to compensate. “Could you tell your readers,” she said.

But Vasyl, 63, out with his grandson Nikita, 13, a young ice hockey player who had just stayed with a Trump-supporting family in Colorado, said he was pleased with the Republican’s victory. “He has promised that the war will be over,” Vasyl said, adding that he hoped Trump would reach a peace deal with Putin.

Vasyl said Russia should be allowed to take control of the territories it has occupied in return for peace because “the best category of our people are dying” and that Russia “had the strength” to prevent any effective counterattack. But the two split over whether Ukraine should join Nato: the teenager said yes emphatically while Vasyl was more equivocal, arguing economic recovery was more important.

Zelenskyy’s former press secretary, Iuliia Mendel, wrote for the Kyiv Post that neither Trump or the defeated Kamala Harris “offered a clear win for Ukraine” and that the near threeyear long war “is steadily eroding the very foundation of the Ukrainian nation”. A ceasefire that offered Ukraine a chance to recover, “may be the best we can hope for in the near term”, she said.

Trump’s aides have previously sketched out a possible “peace deal”. It would involve giving Ukraine’s eastern regions to Russia, with the existing frontline frozen, as well as Crimea, seized in 2014. Russia currently controls about 20% of Ukraine’s territory.

In an interview with the Guardian in May, Zelenskyy made clear that formula was unacceptable. Nor would he be willing to accept a Russian “ultimatum” that forced Ukraine to abandon integration with Europe and future membership of Nato, he said.

Zelenskyy acknowledged that a re-elected Trump could, if he wanted to, impose a military defeat on his country. “Ukraine, barehanded, without weapons, will not be able to fight a multimillion [Russian] army,” he admitted.

If this did happen there would be grave consequences for the US’s standing in the world – as well as for Trump personally. “Does he want to become a loser president? Do you understand what can happen?” Zelenskyy said in May.

Matthew Savill, the military sciences director at the Rusi thinktank, said Russia was now likely to “press home its advantage in numbers” on the battlefield. He added: “Trump’s desire for a deal – and probably a quick one – does not bode well for sustained US support, especially with the current pressure on Ukraine.”

Moscow, meanwhile, is likely to have demands of its own in any Trump-brokered negotiations. In 2022 it formally “annexed” four Ukrainian provinces: Donetsk, Luhansk, Zaporizhzhia and Kherson.

Russia controls almost all of Luhansk oblast, but has only partial control of the other three. Putin is likely to demand their handover, which would mean Ukraine yielding key cities including Zaporizhzhia and Kherson.

Other probable demands include a buffer zone, “reparations” for damage done to Russian-occupied Donbas, and a guarantee of Ukraine’s non-Nato “neutrality”. All would be unacceptable to Kyiv and to a majority of Ukrainians.