US President Donald Trump is considering sending long-range Tomahawk cruise missiles to Ukraine.

Asked by reporters on Air Force One on Sunday whether he would provide Kyiv with Tomahawks, Trump replied: "We'll see... I may". The missiles would be "a new step of aggression" in Ukraine's war with Russia, he said.

The comments follow a phone call at the weekend between Trump and Ukrainian President Volodymyr Zelensky, who pushed for stronger military capabilities to launch counter-attacks against Russia.

Moscow has previously warned Washington against providing long-range missiles to Kyiv, saying it would cause a major escalation in the conflict and strain US-Russian relations.

Tomahawk missiles have a range of 2,500 km (1,500 miles), which would put Moscow within reach for Ukraine.

Trump said he would possibly speak to Russia about the Tomahawks requested by Ukraine.

"I might tell them [Russia] that if the war is not settled, that we may very well, we may not, but we may do it."

"Do they [Russia] want Tomahawks going in their direction? I don't think so," the US president added.

On Sunday, Kremlin spokesman Dmitry Peskov said the topic of Tomahawks was of "extreme concern" to Russia. "Now is really a very dramatic moment in terms of the fact that tensions are escalating from all sides," he said.

In September Peskov dismissed the threat of Tomahawks, saying they would not be able to "change the dynamic" of the war.

But in his comments on Sunday he noted that if Tomahawks were launched at Russia Moscow would not be able to tell whether they were carrying nuclear warheads.

"What should the Russian Federation think? Just how should Russia react?", he said.

On Monday morning former Russian President Dmitry Medvedev doubled down on Peskov's comments.

"How should Russia respond? Exactly!" Medvedev said on social media.

"The delivery of these missiles could end badly for everyone. And first of all – for Trump himself," he wrote.

Medvedev, who over the last few years has grown into an increasingly hawkish figure, frequently posts on social media espousing more extreme positions than the Kremlin's.

He and Trump have sparred online before. Comments by Medvedev in August led Trump to say he had ordered two nuclear submarines to move closer to Russia.

Since the start of Russia's full-scale invasion in 2022, Kyiv has made multiple requests for long-range missiles, as it weighs up striking Russian cities far from the front lines of the grinding conflict.

In their recent phone calls, Zelensky and Trump discussed Ukraine's bid to strengthen its military capabilities, including boosting its air defences and long-range arms.

Ukrainian cities including Kyiv have repeatedly come under heavy Russian bombardment with drones and missiles. Russia has particularly targeted Ukraine's energy infrastructure as winter approaches, causing widespread power cuts.

Last month, Trump's special envoy to Ukraine Keith Kellogg suggested the US president had authorised strikes deep into Russian territory, telling Fox News "there are no such things as sanctuaries" from attacks in the Russia-Ukraine war.