The UK’s recent push for a “buy British by default” approach to defence procurement faces significant practical and strategic challenges, industry experts say, highlighting the complexities of achieving military self-sufficiency in a globalized supply environment.

While the call to prioritize domestic defence manufacturers evokes a wartime spirit, the reality of modern defence supply chains complicates such ambitions. Beyond major contractors like BAE Systems and Rolls-Royce, smaller firms such as Alloyed—an Oxford University spin-off developing low-cost turbojet engines for drones—and Jaguar Land Rover, seeking military vehicle contracts, stand to benefit from the policy. However, defence production relies heavily on intricate international networks. Both large prime contractors and specialized manufacturers source components from numerous suppliers worldwide, making total national independence difficult to sustain.

Moreover, many UK defence companies, especially startups, depend on foreign investment. For example, Berlin-based drone supplier Stark, recently contracted by the German military, is backed by US technology entrepreneur Peter Thiel. This international financial interdependence further complicates efforts to fully “buy British.”

Critics of the policy argue that attempting to foster national champions often leads to duplicated efforts and inefficiencies, with different countries developing overlapping capabilities that rely heavily on a limited number of government contracts. This dependency can be precarious; in the UK, for instance, former defence secretary John Healey’s ambitious goal of spending 3% of GDP on defence by 2030 has reportedly been reconsidered since his appointment as chancellor.

Given these constraints, many defence experts advocate for closer collaboration with allied nations as a more viable strategy. Joint ventures offer a means to pool resources, share technological expertise, and access broader markets. The European missile manufacturer MBDA—co-owned by BAE, Airbus, and Italy’s Leonardo—serves as a successful example, having increased sales by 17% last year, outpacing each of its three parent companies.

Germany’s Rheinmetall, which has gained prominence following Russia’s invasion of Ukraine in 2022, has embraced this model aggressively. Since late 2023, Rheinmetall has entered into 21 joint ventures and partnerships, citing benefits such as expanded capacity, technology access, market reach, and capital.

Collaboration with trusted allies also helps mitigate risks associated with delays and cost overruns. The UK’s recent record on major defence projects shows that 47 of 49 programs have faced delays or budget increases, underscoring the challenges of delivering on ambitious national plans independently.

For governments aiming to maintain tight control over defence procurement, fostering international partnerships appears to offer a more sustainable and efficient path forward than striving for unilateral self-reliance.