UK PM responds to Putin’s threat that use of long-range British missiles inside Russia would put it at war with Nato

Keir Starmer and foreign secretary David Lammy boarding a plane to Washington DC on Thursday. Photograph: Stefan Rousseau/Reuters

Keir Starmer has told Vladimir Putin that he started the war in Ukraine and could end it at any time after the Russian leader warned that any use of long-range British missiles into Russian territory would put Nato at war with his country.

The prime minister spoke en route to Washington to see US president Joe Biden as he sought to justify a western decision made behind closed doors that would allow Ukraine to attack inside Russia with partly British-made Storm Shadow missiles.

Responding directly to threats earlier by the Russian president, Starmer told reporters: “Russia started this conflict. Russia illegally invaded Ukraine. Russia can end this conflict straight away. Ukraine has the right to self-defence.”

The UK, he added, had provided “training and capability” – a reference to weapons – to help Ukraine repel the Russian invasion and said that he was visiting the US president partly because “there are obviously further discussions to be had about the nature of that capability”.

A day earlier, the Guardian revealed that the US and UK had agreed, in conjunction with other allies, to allow Ukraine to strike military targets inside Russia with Storm Shadow missiles, which have a range of at least 190 miles, a longstanding demand of Kyiv’s.

On Thursday, Putin said any western move to let Kyiv use such longer-range weapons against targets inside Russia would mean Nato would be “at war” with Moscow – a dramatic escalation of his rhetoric about the war which began with the Russian invasion in February 2022.

“This would in a significant way change the very nature of the conflict,” Putin told a state television reporter. “It would mean that Nato countries, the US, European countries, are at war with Russia,” he said, adding that Russia would take “appropriate decisions based on the threats that we will face” as a result.

Starmer was speaking on a plane to Washington DC as he headed for a special foreign policy summit with Biden on Friday. The prime minister said that he would not comment on Storm Shadow directly, but added he wanted to ensure that “all the decisions we made are within the strategic context” by discussing the issues with his US counterpart at the White House on Friday afternoon.

“There are really important developments likely in the next few weeks and months, both in Ukraine and the Middle East, and therefore a number of tactical decisions ought to be taken,” the prime minister said.

David Lammy, the foreign secretary, appeared to go a step further on Thursday night, saying Britain and the US should give Ukraine the weapons it needs to defeat Russia. “This is a crucial period in the fight because you are setting things up to stop Russia getting the advantage over winter,” he told the Daily Telegraph while ­visiting Kyiv.

“We are here also, of course, at a time when it is crystal clear Russia is escalating with its friend Iran, taking a consignment of ballistic missiles. Ballistic missiles that will be used in the winter, sadly, against the Ukrainian people and which will cost lives.

“So, of course, we’re here to strategise, to understand how we can put Ukrainians in a position to win and what is needed.”

Ukraine has been lobbying to use Storm Shadow and US-made Atacms missiles for many months, complaining that while Moscow has been able to repeatedly bomb targets across Ukraine since the start of the war, it has been prevented from hitting military targets inside Russia.

However, Biden had been reluctant to authorise a retaliation because of a fear of escalating the conflict with Russia. But the situation changed earlier this week when the US and UK said that Russia had taken delivery of the first shipment of Fath-360 short-range ballistic missiles from Iran.

Nevertheless, the US and UK have emphasised to Ukraine and its president, Volodymyr Zelenskiy, that any use of Storm Shadow missiles must be carefully coordinated as part of a wider plan to try to force Russia to end the conflict which is now heading towards its third winter.

No press conference involving Biden and Starmer is planned, and any first announcement of the use of Storm Shadow inside Russia is likely only if an attack with the missiles is made. Its impact would be too noticeable to be concealed.

Starmer emphasised the purpose of the trip, during which he will have about three hours of talks with the outgoing Biden on Friday, was to have “a strategic discussion” about Ukraine, Gaza and other foreign policy questions.

But he added it was not to try to force a peace agreement on Ukraine. “Ultimately that’s a discussion that has to be led by President Zelenskiy,” Starmer said. Instead, he said, “it’s very important for two key allies” to discuss foreign policy questions “among themselves and to have spaces to do that”.

The prime minister will first have a short one-to-one meeting with the president, who is due to step down in January, before switching to a wider meeting involving David Lammy, the foreign secretary, and other key officials, UK ambassador to the US Karen Pierce and Tim Barrow, the national security adviser.

But the prime minister will not meet Kamala Harris, the vice-president and Democrat nominee, because she was campaigning ahead of the November election. “She will be in other parts of the US,” he said. “Rather than Washington, she’ll be, as you’d expect, in swing states.”