UK lets Ukraine build “Stone Cloak” jammer to scale long-range drone strikes

Key facts

• UK disclosed Stone Cloak, a British-designed digital radar jammer intended for use on Ukrainian long-range strike drones.
• A new tech-sharing agreement allows Ukraine to manufacture Stone Cloak domestically to scale deployment across drone forces.
• The announcement coincided with Sea Breeze-related UK-Ukraine engagement, with reported focus on countering Russian air defences.

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The UK has announced that it will allow Ukraine to manufacture a British-designed digital radar jammer known as Stone Cloak, a move aimed at accelerating the scale and effectiveness of Ukraine’s long-range strike drone operations against Russian targets. The device is described as roughly the size of a computer tablet and has reportedly already been fielded this year on Ukrainian long-range strike drones in UK-built form; the new element is an agreement enabling Ukrainian mass production, which should shorten replenishment cycles and enable broader fleet-wide integration.

The disclosure came during high-level UK-Ukraine engagement at Portsmouth in conjunction with the annual Sea Breeze exercise, where Ukrainian, US and UK naval personnel reportedly placed emphasis on countering Russian air defences. Although public details on Stone Cloak’s technical parameters are sparse, independent commentary cited by the source assesses it as likely to increase mission effectiveness against elements of Russia’s air-defence architecture. In practical terms, an onboard jammer adds an additional layer of survivability to low-cost, long-range unmanned strike systems that increasingly rely on electronic attack, navigation resilience and signature management to penetrate defended airspace.

For European defence officials and industry, the more consequential signal is the policy and industrial precedent: IP sharing for front-line EW payloads is rarer than the transfer of complete weapons, and it implies a higher level of trust, export-control accommodation and production oversight. The article contrasts this with prior UK support for Storm Shadow, where missiles were transferred but design technology was not, in part due to multinational supply chains and partner involvement. Stone Cloak, by comparison, appears positioned as a scalable subsystem that can be manufactured and iterated in Ukraine, reflecting a different model of capability delivery built around modular payloads and rapid upgrade cycles.

The broader context is a widening UK-Ukraine collaboration on long-range strike, including the 2024 “Breakstop” effort to develop a simplified, lower-cost long-range strike drone on a timeline reported as under 24 months, alongside Ukraine’s own lower-cost cruise-missile initiatives such as the Flamingo (FP-5). The recurring operational lesson highlighted is Ukraine’s exceptionally rapid adaptation cycle—sometimes implementing battlefield feedback in days—which, if systematically harnessed through joint trials and co-development, could materially benefit European EW, counter-IADS concepts and uncrewed strike portfolios. For Europe, this points to Ukraine as not only a recipient but a high-tempo test-and-iteration partner whose combat data can compress development timelines for EW-enabled uncrewed systems—provided governance, security and industrial capacity constraints are managed.

Source: Defense One