Volodymyr Zelenskyy has appealed to global leaders to intervene to prevent Russia from leading the world through “the most destructive arms race in human history”, warning that the combination of drone technology and artificial intelligence would end in catastrophe.

Speaking to the UN general assembly, the Ukrainian president tried to galvanise not just the west but also China. His chilling account of how Russia is using technology to change the face of war was the opposite of Donald Trump’s claim that Russia’s military may only be a paper tiger.

He warned that Vladimir Putin, unchecked, would use drones to expand his war throughout Europe. “The facts are simple. Stopping this war now, and with it the global arms race, is cheaper than building underground kindergartens or massive bunkers for critical infrastructure later,” he told the UN. “Stopping Putin now is cheaper than trying to protect every every port and every ship from terrorists. Stopping Russia now is cheaper than wondering who will be forced to create a simple drone with a nuclear warhead.”

Ten years ago, he said, “war looked different and no one could have imagined that cheap drones could create death zones stretching for dozens of kilometres where nothing moves, no vehicles, no life. People used to imagine that only after a nuclear strike. Now it is drone reality, and without AI yet.”

Referring to the recent wave of Russian disruption across Europe, including a drone incursion into Poland, he said: “Putin was intent on driving the war forward, wider and deeper … to continue this war by expanding it.”

He said he warned Europe before about Russia’s intentions “and now Russian drones are flying across Europe”. No one could be immune from the spread of war, he said, adding: “We are living through the most destructive arms race in human history.”

Zelenskyy gave no overall evaluation of the war in Ukraine nor did he refer directly to Trump’s surprise claim it would be possible for Ukraine to recapture all the lands that it had lost to Russia since 2022, saying simply he had had a good meeting on Tuesday with the US president.

He said in the modern world “only friends and weapons” protected countries, and not international law or UN resolutions. But he said every country faced a choice between peace or helping Russia by continuing to trade with Moscow. Those that continued to fund the war consigned prisoners of war, abducted children and hostages to longer periods of captivity, he said.

Zelenskyy also warned that Europe could not afford to lose neighbouring Moldova to Russian influence. The country’s prime minister, Dorin Recean, on Wednesday claimed Russia was spending hundreds of millions of euros to “take power” in a pivotal parliamentary election that could derail Moldova’s course toward the European Union.

Before Zelenskyy’s speech, Moscow had brushed off the shift in tone from Trump, including his claim Russia had been “fighting aimlessly for three and a half years”, a stark contrast to the red-carpet treatment he laid out for Putin at a summit in Alaska last month.

The Kremlin spokesperson, Dmitry Peskov, attributed the comments to the fact Trump had just met Zelenskyy on the sidelines of the UN general assembly in New York.

In an interview with RBC radio, Peskov said: “Of course, President Trump heard Zelenskyy’s version of events. And apparently at this point, this version is the reason for the assessment we heard.”

Peskov said the Russian army was making gains in Ukraine, albeit slowly. Putin “has repeatedly stated this – we are moving forward very carefully to minimise losses … These are very deliberate actions,” he said.

Peskov dismissed the description of Russia as a “paper tiger”, saying his country was a bear, the national animal. “Russia maintains its resilience. Russia maintains macroeconomic stability,” he said.

In later statements, the Kremlin said the war was not aimless, and it appeared to attempt to placate Trump by saying the process of restoring relations between Russia and the US was proceeding “much more slowly than desired”.

On Tuesday Trump gave an upbeat assessment of Ukraine’s prospects in the war, claiming Russia was in big economic trouble. It was one of the strongest statements of support he had given to Kyiv in recent months.

Writing on his Truth Social platform, Trump said: “After getting to know and fully understand the Ukraine/Russia Military and Economic situation and, after seeing the Economic trouble it is causing Russia, I think Ukraine, with the support of the European Union, is in a position to fight and WIN all of Ukraine back in its original form.”

He said if the Russian public found out what was “really going on with this war”, the Ukrainians could launch a counteroffensive in which they would “take back all the territory occupied by Russia – and, who knows, maybe even go further than that”.

Zelenskyy hailed Trump’s intervention, saying it represented a “big shift” from the US president.

Moscow’s invasion of Ukraine has had a significant impact on the Russian economy, with the finance ministry on Wednesday proposing raising the rate of value-added tax by two percentage points to 22%.

Also on Tuesday, Trump berated European countries for “embarrassing” purchases of Russian oil and gas, demanding they “immediately cease all energy purchases from Russia” or “otherwise we are all wasting a lot of time”.

The EU has sharply reduced its consumption of Russian oil and gas since 2022 and bought 19% of its gas and 3% of oil from Russia in 2024, down from 45% and 27% before the full-scale invasion of Ukraine.

The European Commission president, Ursula von der Leyen, said on Tuesday that she and Trump during a bilateral meeting at the UN had “agreed on the need to cut Russia’s revenues from fossil fuels, and fast”. In her account of the meeting, von der Leyen said: “By 2027, Europe will have turned the page on Russian fossil fuels for good.”

Last week von der Leyen announced plans to phase out Russian liquified natural gas purchases by 2027, a year earlier than planned. The commission also announced plans to expand sanctions to 118 vessels in Russia’s shadow fleet, poorly maintained tankers that are used to transport Russian oil to foreign buyers evading western price restrictions.

But the EU has not yet ended an exemption from buying Russian oil that was granted to Hungary and Slovakia in 2022. Both central European countries have rejected the plan to phase out Russian fossil fuels despite pressure from Trump, an ally of the Hungarian prime minister, Viktor Orbán.

The EU needs unanimity to agree on sanctions, although measures to restrict trade can be approved by a majority. It remains unclear when and how the latest proposals will be agreed, with senior EU diplomats expected to discuss the plans in the coming days.