Britain will allow the release of classified technology so that a British/French-designed cruise missile can be manufactured in Ukraine, a boost for Kyiv in its efforts to bring more firepower to bear hundreds of kilometres into Russia.Paris and Kyiv want to set up a Ukrainian production line for the SCALP air-launched cruise missile, known as the Storm Shadow in the United Kingdom, by the end of the year. The declassification of information on British-made components of the missiles, announced Monday (local time), is a key step towards that goal.Made by European arms manufacturer MBDA, SCALP is a conventionally armed, long-range, deep-strike weapon, of which Ukraine has used imported versions with success against hardened targets, including in November 2024, when they were fired at targets inside Russia for the first time.Powered by a turbojet engine, it has a maximum range of 550km (342 miles) and can carry a 400km (880 pounds) high-explosive penetrating warhead, according to the Missile Threat project at the Centre for Strategic and International Studies (CSIS).Once launched, the missile uses a combination of internal, global positioning and terrain reference navigation coupled with "infrared seeker and automatic target recognition algorithms" to achieve a high degree of accuracy in all weather conditions, according to the CSIS.The SCALP is fired from Ukraine's Su-24 or Mirage 2000 fighter jets and attempts to avoid air defences by hugging the terrain during flight.A low-observable, long range air launched cruise missile displayed at Paris Air Show in 2025.Nicolas Economou / NurPhoto via AFPIts use for Ukraine will be in striking buried military targets, like command bunkers, something more challenging for the lighter weight drones Kyiv has been using to hit more exposed targets like oil refineries or warehouses.The Kremlin reacted angrily to the announcement, with spokesman Dmitry Peskov saying the UK was "participating in the war" and "pouring fuel on the fire".His statement came after the Russian embassy in London warned the UK last week that "the deeper its involvement" and "the greater its support" for Ukraine, the "higher the price it will pay".Britain and France have not announced how many SCALP/Storm Shadow missiles have been supplied to Ukraine to date, but in 2025 manufacturer MBDA reactivated production lines that had been shuttered for 15 years."Supplied to Ukraine, the Franco-British SCALP/Storm Shadow missile has demonstrated its effectiveness in modern high-intensity combat, in decisive situations," French Defence Minister Sébastien Lecornu said at the time.Even with the UK announcement, it could take several years for production to scale up, but British Prime Minister Andy Burnham says London is backing Kyiv for the long haul."The Ukrainian people should be in no doubt: the UK is behind you today and for as long as it takes," Burnham said in a press release Monday announcing that the UK would release its missile technology."Ukraine's security is our security," said the prime minister, who arrived in Kyiv on Monday for Ukraine's independence day, in his first overseas trip since taking office on 20 July.Ukrainian President Volodymyr Zelensky said he was "grateful" to Burnham for his support, saying that he awarded Burnham with the "first new state distinction: Gratitude of the Ukrainian People".The two countries signed an agreement to "develop their partnership in the field of artificial intelligence", Zelensky said.While in Ukraine, Burnham co-chaired a meeting of the Coalition of the Willing, a 34-nation international alliance formed last year by Britain and France to support Ukraine in the war as US aid waned under the Trump administration.The alliance promised to boost Ukraine's air defences on Monday, with Burnham saying Monday that Kyiv's allies need to do "everything we can" to supply more air defences.French President Emmanuel Macron, who joined the meeting remotely, said that the last few weeks have clearly showed that Kyiv's allies "need to accelerate delivery of interceptors", adding that his country will accelerate "everything that we have available".Macron also confirmed that the first full-scale military exercises of the Coalition of the Willing will be conducted in October and November. They will involve British and French forces and take place in Poland.Interceptor struggleWhat the SCALP can't address is Ukraine's shortage of defensive missiles, like the US-designed Patriot system, a vulnerability exposed with devastating consequences in recent weeks as Russia has launched large waves of its own missiles and drones in attacks that have killed dozens of Ukrainians.CNN visited a Patriot battery in Ukraine earlier this month and was told that it had not been fired in weeks because no interceptors were available.Ukraine has asked for permission to manufacture the Patriot interceptors in the country, an idea US President Donald Trump initially supported in early July but later backtracked on.The Trump administration has also rebuffed Ukrainian attempts to acquire long-range US Tomahawk cruise missiles, stocks of which have been taxed by the war in Iran.Ukraine's domestic missile production has not stood still, however.Ukrainian manufacturer Fire Point has developed the FP-5 Flamingo cruise missile.With a range of 3000km, it can strike deep inside Russia, and Zelensky said earlier this month it was used to hit a key Russian rocket electronics facility some 900km from Ukraine's border.The Ukrainian leader said the Flamingo made its combat debut in 2025, and open-source intelligence reports indicate its use has been on the increase this year.Fire Point has also developed long-range drones to go along with shorter range ballistic missiles.Kyiv's use of longer-range weapons has turned Russia's sprawling land mass, once considered a military advantage, into a problem for Moscow as it struggles to allocate limited defensive weaponry to the increasing number of targets within Ukraine's range, Peter Dickinson, editor of the Atlantic Council's Ukraine Alert blog, wrote earlier this month."A long line of would-be conquerors have invaded Russia only for their armies to swallowed up by the vastness of the country. Ukraine is now attempting to turn this military logic on its head with a strategic bombing campaign that aims to exploit Russia's immensity and transform it from a key strength into a fatal weakness," Dickinson wrote.- CNN's Darya Tarasova, Victoria Butenko and Ivana Kottasova contributed reporting.- CNN