Britain's defence investment plan is not fit for purpose

I think I'm going to be hung up on the Defence Investment Plan (DIP) for a while. For entirely self-indulgent reasons I’ve committed to beefing up the defence policy on the Manifesto Project. The DIP has to be at the heart of any policy analysis because it shows us the current assumptions of modern British defence doctrine.

It seems we are all but abolishing helicopters. I partially explored this yesterday but it’s even worse than I assumed. While we are getting a limited number of additional Chinooks, I am reminded that the existing fleet, in terms of airframe hours, is getting on up there. Once retired, the overall number of airframes could plummet.

We then learn that RAF Intelligence, Surveillance and Reconnaissance capabilities are seriously threatened. We are set to see the early retirement of the Shadow R1 (pictured), while the MoD is committed to Project CORVUS: £310m additional investment in long range surveillance and reconnaissance capabilities, including the next generation of uncrewed aerial systems to replace legacy Watchkeeper drones. According to the DIP, up to 24 new surveillance drones will be delivered by 2029.

Less than impressed, RUSI says...

As is found with newer platforms such as Elbit’s 650 Spark or DZYNE Technologies ULTRA, 24 hour endurance, with related sensor payloads, can only realistically be achieved by a UAV in the NATO Class 3 Medium-Altitude Long Endurance (MALE) category.

The decision to acquire such a drone is inconsistent with both the MOD’s assessment of the threat environment and data from contemporary conflicts. Corvus will replace the troubled Watchkeeper drone program which took 14 years to reach full operational capability and was declared obsolete last year by Minister of State Lord Coaker, who argued that lessons from Ukraine showed that MALE UAVs were not survivable. This is in line with a 2020 assessment by the US Air Force which concluded that this class of drones cannot survive in contested airspace.

The vulnerability of such UAVs is currently being demonstrated in Yemen. The Market Engagement Notice for Project Corvus comes after at least 15 US MQ-9 Reaper drones have been shot down over Yemen since late 2023, a toll that spiked after the Trump administration’s renewed air campaign on 15 March 2025. Losses, according to the Houthis, could be as high as 22 airframes, although the group often makes false claims. This is a strong indicator that Corvus is not a sound investment. But that doesn’t mean the Army can do without a means of finding targets.

More damningly, it says...

The Houthis have a long history of rapid tactical innovation alongside their Iranian advisors, and clearly have capable air defences. This was illustrated in 2018 when a Saudi Arabian F-15S, tracked by the Houthis with a FLIR system, deployed flares and accelerated before being hit by a surface to air missile (SAM).

Several US Reapers were lost to the group before the current conflict, including one shot down in 2019 which CENTCOM assessed was engaged with Soviet-era SA-6 and SA-7 SAMs.

More recently, the loitering 358 Saqr Iranian SAM used by the Houthis, Iran-backed militias in Iraq and Hezbollah, have had far more success. Israeli losses of Hermes MALE drones over Lebanon including the 450 model that the Watchkeeper was based on, and the larger 900 model, are more evidence that MALE drones are at acute risk. And yet, the Houthis cannot be considered a peer adversary.

Evidence of MALE drone performance in peer conflict is demonstrated by the near total destruction of Ukraine’s Bayraktar TB2 fleet after a few days of successful strikes at the beginning of Russia’s full-scale invasion of Ukraine, with one Ukrainian pilot calling the drones ‘almost useless’ against Russia’s layered air defences.

The point demonstrated here is that even in the airspace above non-state actors MALE drones lack survivability. But the British Army wants to use such a platform as a Corps reconnaissance asset, and therefore suggests it is to be used in peer-warfighting.

Essentially we’re looking at £310m wasted on something that is conceptually obsolete. For an effective interim solution, the priority should be the rapid acquisition of smaller, low-cost, attritable tactical unmanned systems that can be fielded in much greater numbers. The emphasis must be on resilience through quantity rather than reliance on a small number of exquisite platforms. High-capability ISR assets in a peer conflict are too vulnerable and have become obsolete. The game is now cut-price COTS sensors, widely distributed in a multiplicity of formats - networked via commercial comms and integrated via AI.

RUSI suggests alternative approaches for the UK could include investing in low-earth orbit satellites, and in the near term, sourcing affordable options such as high-altitude balloons in the stratosphere (a current US project) or tethered aerostats (available through UK providers), which support an array of sensors providing surveillance over hundreds of kilometres.

What the DIP shows us is that the MoD is working to outdated models, has not kept abreast of recent developments, and is somehow missing all of the important lessons which are now widely understood in the public domain. As I dig deeper into it, there seems to be a mix of obtusity, naivety and delusion, stitched together with hopeless optimism. As such, it would appear our most urgent problem is the cultural problem inside the MoD and its interface with the treasury. Meanwhile, the likelihood of intelligent media scrutiny is vanishingly small.