Storm Shadow missiles: what are they and why are they important for Ukraine?

When Keir Starmer meets Joe Biden at the White House on Friday, the war in Ukraine – and an expected move to lift restrictions on Ukraine’s use of long-range Storm Shadow missiles – will be at the top of the agenda.

The meeting follows a week of diplomatic choreography between the British and Americans, culminating in the US secretary of state, Antony Blinken, and UK foreign secretary, David Lammy, travelling to Kyiv on Wednesday .

Ukraine has for months been asking for restrictions on the use of western-supplied Storm Shadow missiles to be loosened, but, until now, Kyiv’s allies have been reluctant to give the green light. Owing to the sensitivity and significance of such a decision – which the Guardian reported this week has already been made in private – no official announcement is expected.

What are Storm Shadow missiles, and why does Ukraine want them?

Storm Shadow missiles can hit targets up to 155 miles (250km) from their launch site – meaning they could strike deep into Russian territory. They are powerful enough to penetrate bunkers and ammunition stores and damage airfields, and can be precisely targeted.

They were developed in an Anglo-French collaboration, and manufactured by a joint venture also involving Italy, using components supplied by the US. Consequently, all four countries would have to sign off on any change to the conditions attached to their use, even if they are not the direct suppliers themselves.

Ukraine already has Storm Shadow missiles but it is permitted to use them only within its own territory. Kyiv has been lobbying for months for that to change so it can direct them at targets on Russian soil, arguing it is being hampered in its efforts to defend itself against missile and glide bomb attacks launched against its cities and frontline targets from within Russia. While it does have drones and cruise missiles that can strike within Russia, it does not have enough of them to make a significant impact – and they are often intercepted.

Ukraine has meanwhile used domestically produced long-range drones to strike Moscow and beyond, and its operations have been increasingly successful. On Monday a drone attack shut three Moscow airports . Another strike this month damaged an oil refinery on the outskirts of the capital .

Speaking to the Guardian in May , the Ukrainian president, Volodymyr Zelenskiy, said Biden’s equivocation and incremental approach to providing western weapons had cost lives. It allowed the Kremlin to “hunt” Ukrainians, he complained.

Why has the west not allowed Ukraine to use the missiles in Russia?

Throughout the war, the US and its allies have sought to strike a balance between giving Ukraine the weapons it needs to defend itself while avoiding any move that could be viewed as a provocation and lead to direct involvement in the war.

On Thursday, Vladimir Putin said any western decision 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,” the Russian president told a state television reporter. “It would mean that Nato countries, the US, European countries, are at war with Russia. He added that Russia would take “appropriate decisions based on the threats that we will face” as a result.

What has changed?

Several factors. Ukraine is facing a lot of pressure on the frontline, and fears a difficult winter ahead. Its surprising cross-border incursion into Kursk last month has reframed thinking on the use of weapons on Russian soil and acted as a reminder that Ukraine is at its most effective when it is changing the dynamic of the conflict.

Matthew Savill , the director of military sciences at the defence thinktank Rusi in London, said Ukraine had not briefed allies in advance about its incursion into Kursk. “It changed the debate about escalation and the use inside Russia of long-range weapons,” he said.

There was also news this week that Russia had received a new batch of ballistic missiles from Iran.Lammy suggested on Wednesday that this had changed strategic thinking in London and Washington

In August, Politico reported that Ukrainian officials visiting Washington would present a list of long-range targets within Russia that could be hit. While the White House has argued that Russia has been moving key assets out of range, it now appears to have been persuaded that enough meaningful targets are available to have an impact.

What are the benefits and risks of allowing Storm Shadow to be used within Russia?

There is an inherent tension in how Ukraine believes the weapons can be effective: by degrading Russia’s ability to strike against targets in Ukraine, but also by bringing the war further on to Russian soil, in theory thereby making the costs to Putin more acute.

Despite having lost between 68,000 and 150,000 soldiers, according to some estimates , and with hundreds of thousands more wounded, Putin does not appear to have paid any significant political cost. Making ordinary Russians more fearful of the consequences of the war in Ukraine might make him pay more attention. But that is a narrow tightrope to walk.

A strike that caused many civilian casualties could be very problematic for the west, and if it was caused by a Storm Shadow missile it would be very hard to deny western involvement.

Savill also cautioned that it would be “very, very hard to knock out” Russian airbases, which were “mostly lots of concrete” and “hundreds of kilometres” beyond the frontline. ATACMS missiles with cluster bomblets would be more effective than non-cluster-armed Storm Shadows, he suggested.