The United Kingdom continues to deepen its support for Ukraine, moving beyond weapons deliveries and financial aid into an entirely new level of defense cooperation. London has transferred the intellectual property rights for the Stone Cloak electronic warfare (EW) system to Ukraine, enabling domestic production, modernization, and further development by Ukraine's defense industry.
The decision was announced by the British government following a meeting between Ukrainian President Volodymyr Zelenskyy and UK Prime Minister Andy Burnham. The British prime minister described Stone Cloak as "one of Britain's finest innovations, proven on the battlefield, and one that will be critical to the security of both our countries."
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Very little is currently known about Stone Cloak. The system is designed for installation on UAVs and cruise missiles, including those being developed under the Brakestop program. According to the information released so far, the unit is roughly the size of a tablet computer and "prevents russian air defense systems from tracking and engaging targets." The UK has already delivered thousands of Stone Cloak systems to Ukraine.
The identity of the developer has not been disclosed, and no official hints have been provided. However, one of the UK's leading developers of airborne electronic warfare systems is BAE Systems, which supplies EW suites for combat aircraft, including the F-35 and F-15EX. The company is also developing the Nightshade electronic warfare system for drones.
What is particularly significant is that the British government either acquired the intellectual property rights itself or commissioned the system's development directly. Otherwise, London would have been unable to transfer those rights to Ukraine. This arrangement gives Ukraine the ability not only to manufacture Stone Cloak domestically but also to integrate the technology into both existing and future Ukrainian cruise missiles, in addition to drones.
Based on the limited information currently available, Stone Cloak appears to operate more like an aircraft self-protection electronic warfare suite than a traditional ground-based jammer. Such systems detect hostile radar emissions, analyze them, and generate electronic countermeasures. However, Stone Cloak reportedly achieves this in a package small enough to fit inside a drone, with low power requirements and, judging by the number delivered, a relatively low production cost.
That strongly suggests the system is not designed to overwhelm enemy radars with powerful jamming signals. A more plausible explanation is that it employs sophisticated electronic deception, creating false targets on radar displays and/or distorting the drone's radar signature, making it significantly more difficult for enemy air defense systems to establish a reliable track and guide interceptors.
Such a capability could substantially improve the survivability of Ukrainian drones and cruise missiles penetrating russian air defenses. This is especially relevant given that russian surface-to-air missile systems have repeatedly demonstrated inconsistent effectiveness against Ukrainian long-range drones. One notable example was Ukraine's successful strike on targets near Moscow despite the area's protection by dozens of Pantsir systems and at least three S-400 batteries. At the same time, Ukrainian drones themselves have become one of the primary means of destroying russian air defense systems.
Another interesting aspect is that, despite thousands of Stone Cloak units already being supplied to Ukraine, russia appears not to have publicly identified the system. At least so far, there have been no known russian technical analyses describing the recovery or examination of Stone Cloak electronic warfare modules from downed Ukrainian drones.
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