ISC Defence Intelligence summary card, 23 June 2026. Official MBDA UK imagery of the CROSSBOW firing is embedded below from the company’s verified channel.

Project Brakestop: UK Flight-Tests Low-Cost 500 km Strike Munitions as the MoD Sets a Twenty-a-Month Production Bar

Technical Summary

On 22 June 2026 the United Kingdom Ministry of Defence (MoD) confirmed that three British-designed long-range strike systems developed under Project Brakestop have completed flight testing. Brakestop was launched in November 2024 by Taskforce Kindred, an MoD rapid-acquisition cell, with a deliberately austere requirement: a ground-launched strike munition able to reach beyond 500 kilometres (km), carry a warhead of at least 225 kilograms (kg), fly faster than 600 kilometres per hour (km/h), cost about 400,000 pounds sterling (GBP) per round excluding the warhead, and be manufacturable at a rate of at least twenty rounds per month within months of a production order. A further condition shaped the engineering from the start: each system had to be free of United States components and navigation data. That sovereignty stipulation, driven by the intent to furnish Ukraine with deep-strike capability free of an external veto on targets or timing, keeps export and targeting decisions under United Kingdom control and places the programme inside the wider European move toward strike weapons that sit outside the United States International Traffic in Arms Regulations (ITAR).

Twenty-seven bids were received when the competition opened. After technical assessment and competitive pitches in February 2025, six firms each took a contract worth about GBP 5 million to build prototypes inside seven months. By December 2025 three suppliers remained and test-fired their effectors at the MoD Hebrides Range, a site managed by QinetiQ under the Long-Term Partnering Agreement, in trials that ran between December 2025 and February 2026 ahead of the 22 June announcement: MBDA UK, manufacturer of the Storm Shadow stand-off cruise missile, fielding a turbojet-powered effector named Crossbow; MGI Engineering, a Formula 1 engineering small and medium-sized enterprise for which Brakestop is a first defence contract, fielding the composite-airframe TigerShark; and Rotron Aerospace, a small and medium-sized enterprise with a record in rotary-engine propulsion for uncrewed systems, fielding the propeller-driven SkyLance. Follow-on Phase 2 contracts worth about GBP 15 million each now fund multiple suppliers to build fifteen improved effectors apiece, together with launchers and support vehicles, with further trials planned in the United Kingdom and then overseas, including in Ukraine.

MBDA announces successful #CROSSBOW firings, marking a key milestone in ground-launched #DeepStrike. Conducted in Dec 2025 and Feb 2026, it moved from design to demonstration in nine months. Its modular design delivers range, lethality and survivability.

MBDA UK (@MBDA_UK) June 2026

Primary source: MBDA UK official channel (@MBDA_UK), reporting the CROSSBOW firings of December 2025 and February 2026. Post embedded under X Terms of Service; the imagery remains the copyright of MBDA UK and is not reproduced or hosted by ISC.

A required cruise speed above 600 km/h, roughly Mach 0.5 at low level, places Brakestop in the slow, attritable one-way-attack band rather than the high-subsonic cruise-missile class of Storm Shadow. The trade is deliberate: numbers over survivability. ISC technical assessment, 23 June 2026

Analysis of Effects

The open figures describe a ground-launched one-way-attack (OWA) effector rather than a reusable platform. A cruise speed above 600 km/h equates to about 167 metres per second, close to Mach 0.5 in the low-altitude band, which is materially slower than an air-launched cruise missile such as Storm Shadow that transits in the high-subsonic region near Mach 0.8. The design therefore trades survivability for unit cost and volume. The 225 kg warhead is substantial, sitting in the same mass class as a 500-pound (227 kg) aircraft bomb body though about half the roughly 450 kg warhead carried by Storm Shadow, and the MoD states the warhead has already been developed and proven by a separate British firm. That points to a common government-furnished payload integrated across all three competing airframes. Warhead type is not disclosed. On a blast-fragmentation fill at a typical 30 to 45 percent charge-to-weight ratio, the net explosive quantity (NEQ) would fall in the order of 70 to 100 kg of trinitrotoluene (TNT) equivalent, a figure offered only as a planning band because no fill is stated in open sources.

The genuinely novel requirement is industrial rather than ballistic: at least twenty rounds a month within months of a production order, at about GBP 400,000 per round excluding the warhead. That rate-and-cost clause is the centre of gravity. It places Brakestop alongside the affordable-mass deep-fires concepts now emerging across the North Atlantic Treaty Organization (NATO), including other European ground-launched cruise efforts and United States low-cost cruise-missile programmes, and it mirrors the high-volume one-way-attack munitions that have come to define deep strike in Ukraine. A 500 km class effector at this price is roughly an order of magnitude cheaper than a conventional cruise missile, which is precisely what makes mass affordable.

Personnel and Safety Considerations

Delivery drew on a combined MoD team that included the Defence Science and Technology Laboratory (Dstl), 744 Naval Air Squadron, the Air and Space Warfare Centre, and 11 Explosive Ordnance Disposal (EOD) Regiment. The presence of an EOD regiment reflects the range-safety and post-firing clearance burden inherent in trials of a live-warhead munition. A mass-produced 225 kg energetic store also raises through-life questions that sit under United Kingdom ordnance regulation: classification and net explosive quantity determination for storage and transport licensing under the Defence Safety Authority's Defence Ordnance, Munitions and Explosives regulations (DSA 03.OME); hazard division and compatibility group assignment per packaged configuration; and insensitive-munitions characterisation. None of these are addressed in open reporting at this stage, and all bear directly on the storage footprint a twenty-a-month line would generate.

Data Gaps

Several parameters remain undisclosed in open sources and should be closed before any capability or cost comparison is treated as settled: the warhead type, whether blast-fragmentation, penetrating or carrying submunitions, and its net explosive quantity; the propulsion class of the MGI TigerShark, where the MBDA Crossbow is turbojet-powered and the Rotron SkyLance propeller-driven but MGI's airframe is described only by its composite construction; guidance and terminal accuracy, including circular error probable and what supplements the sovereign non-United States navigation solution beyond MBDA's stated in-house visual navigation; the all-up-round hazard division and compatibility group; the exact number of Phase 2 suppliers, stated only as multiple; and the unit cost inclusive of the warhead, as the published GBP 400,000 figure explicitly excludes it.

Corrections & updates welcome. If you hold open-source data that refines or corrects any parameter in this article, please contact [email protected] citing the specific claim and your source. Verified corrections will be incorporated and credited in the revision history. AI-assisted technical assessment based on open-source material. Not a formal intelligence product.