Former Russian president Dmitry Medvedev said Monday that supplying U.S. Tomahawk missiles to Ukraine could end badly for everyone, especially President Donald Trump.

Medvedev, an arch-hawk who has repeatedly goaded Trump on social media, said it is impossible to distinguish between Tomahawk missiles carrying nuclear warheads and conventional ones after they are launched – a point that President Vladimir Putin's spokesman has also made.

"How should Russia respond? Exactly!" Medvedev said on Telegram, appearing to hint that Moscow's response would be nuclear.

Trump said again Sunday that he might offer long-range Tomahawk missiles that could be used by Kyiv if Putin does not end the war in Ukraine.

"Yeah, I might tell him [Putin], if the war is not settled, we may very well do it," Trump said. "We may not, but we may do it... Do they want to have Tomahawks going in their direction? I don't think so."

Medvedev wrote: "One can only hope that this is another empty threat... Like sending nuclear submarines closer to Russia."

He was alluding to Trump's statement in August that he had ordered two nuclear subs to move closer to Russia in response to what he called "highly provocative" comments from Medvedev about the risk of war.

Putin has said supplying Ukraine with Tomahawks – which have a range of 2,500 km (1,550 miles) and could therefore strike anywhere within European Russia, including Moscow – would destroy relations between the United States and Russia.

Ukrainian President Volodymyr Zelenskyy said Ukraine would only use Tomahawk missiles for military purposes and not attack civilians in Russia, should the U.S. provide them.