Ukraine said Russia fired a new kind of missile at the city of Dnipro on Thursday and while there was debate over what kind, it appeared to be a nuclear-capable weapon that carried multiple warheads, in a further escalation of the 33-month-old war.

Kyiv said Russia used an intercontinental ballistic missile (ICBM), a weapon designed for long-distance nuclear strikes and never before used in war. Three US officials said it was an intermediate-range ballistic missile with a smaller range.

In Moscow, President Vladimir Putin said in a televised address that Russia launched a medium-range ballistic missile attack on a Ukrainian military facility in response to recent Ukrainian long-range strikes with Western weapons.

Regardless of its classification, the latest strike highlighted rapidly rising tensions in the past several days.

Ukraine fired US and British missiles at targets inside Russia this week despite warnings by Moscow that it would see such action as a major escalation. Russia’s ambassador in London said on Thursday that Britain was now “directly involved” in the war in Ukraine.

Security experts said that if the Dnipro strike involved an ICBM, it would be the first use of such a missile in war. ICBMs are strategic weapons designed to deliver nuclear warheads and are an important part of Russia’s nuclear deterrent.

Intermediate-range ballistic missiles have a range of 3,000-5,500 kilometres.

“Today there was a new Russian missile. All the characteristics speed, altitude are [of an] intercontinental ballistic [missile]. An expert [investigation] is currently underway,” Ukrainian President Volodymyr Zelenskiy said in a video statement.

Ukraine’s foreign ministry urged the international community to react swiftly to the use of what it said was “the use by Russia of a new type of weaponry.”

Ukraine’s air force said the ICBM targeted Dnipro in central-eastern Ukraine and was fired from the Russian region of Astrakhan, more than 700km away. It did not specify what kind of warhead the missile had or what type of missile it was. There was no suggestion it was nuclear-armed.

“Whether it was an ICBM or an IRBM, the range isn’t the important factor,” said Fabian Hoffmann, a doctoral research fellow at Oslo University who specialises in missile technology and nuclear strategy.

“The fact that it carried a MIRV (Multiple Independently targetable Reentry Vehicle) payload is much more significant for signalling purposes and is the reason Russia opted for it. This payload is exclusively associated with nuclear-capable missiles.”

Russia also fired a Kinzhal hypersonic missile and seven Kh-101 cruise missiles, six of which were shot down, the Ukrainian Air Force said, adding that the attack targeted enterprises and critical infrastructure in Dnipro, the air force said.

Dnipro was a missile-making centre in the Soviet era. Ukraine has expanded its military industry during the war but keeps its whereabouts secret.

The air force did not say what the ICBM targeted or whether it had caused any damage, but regional governor Serhiy Lysak said the missile attack damaged an industrial enterprise and set off fires in Dnipro. Two people were hurt.

Prior to Putin’s comments, Kremlin spokesman Dmitry Peskov told reporters to contact the Russian military for comment when asked about the Ukrainian air force statement.

Ukrainska Pravda, a Kyiv-based media outlet, cited anonymous sources saying the missile was an RS-26 Rubezh, a solid-fuelled intercontinental ballistic missile with a range of 5,800km, according to the Arms Control Association.

The RS-26 was first successfully tested in 2012 and is estimated to be 12 metres long and weigh 36 tonnes, according to the Centre for Strategic and International Studies (CSIS). It said the RS-26 could carry an 800-kilogramme nuclear warhead.

The RS-26 is classified as an ICBM under a nuclear arms reduction treaty between the United States and Russia, but it can be seen as an intermediate-range ballistic missile when used with heavier payloads at ranges below 5,500km, the CSIS said.

‘Totally unprecedented’

A group of glowing projectiles could be seen plummeting to the ground from the night sky in a video published by Come Back Alive, a Ukrainian military charity. It said the video was of Dnipro overnight.

Nato did not respond to a request for comment. The US European Command said it had nothing on the reported use of an ICBM and referred questions to the US Department of Defence.

“If true this will be totally unprecedented and the first actual military use of ICBM. Not that it makes a lot of sense given their price and precision,” Andrey Baklitskiy of the UN Institute for Disarmament Research posted on X.

German security expert Ulrich Kuehn posted: “It looks as if Russia has today used an ICBM in a war for the first time in history, against the civilian target Dnipro.”

Some military experts said the ICBM launch, if confirmed, could be seen as an act of deterrence by Moscow following Kyiv’s strikes into Russia with Western weapons this week after restrictions on such strikes were lifted.

Russian war correspondents on Telegram and an official speaking on condition of anonymity said Kyiv fired British Storm Shadow cruise missiles into Russia’s Kursk region bordering Ukraine on Wednesday.

Russia’s defence ministry, in its daily report of events over the previous 24 hours on Thursday, said air defences had shot down two British Storm Shadow cruise missiles but did not say where. Britain had previously let Ukraine use Storm Shadows only within Ukrainian territory.

Ukraine also fired US ATACMS missiles into Russia on Tuesday after US President Joe Biden gave the all-clear to use such missiles in this way, two months before he leaves office and Donald Trump returns to the White House.

Putin on Tuesday lowered the threshold for a nuclear strike in response to a broader range of conventional attacks.

Trump has said he will end the war, without saying how, and has criticised billions of dollars in aid for Ukraine under Biden. The warring sides believe Trump is likely to push for peace talks — not known to have been held since the war’s earliest months — and are trying to attain strong positions before negotiations.

Moscow has said the use of Western weapons to strike Russian territory far from the border would be a major escalation in the conflict. Kyiv says it needs the capability to defend itself by hitting Russian rear bases used to support Moscow’s February 2022 invasion.