Europe’s rearmament is usually measured in production lines, munitions output and platform orders. Complex military systems, however, also have to be specified, integrated, tested, certified, modified and supported, and their configuration has to be controlled throughout service lives that can extend for decades. Much of that work does not sit permanently inside ministries of defence or prime contractors. It is bought from engineering consultancies, test houses, research institutes, software specialists and smaller technical firms, sometimes as individual specialists placed in customer teams and sometimes as complete packages of work for which the supplier answers. Higher procurement volumes and faster modification cycles increase demand for precisely these functions, because every new order, supplier substitution or upgrade generates design changes, test campaigns, safety arguments and configuration updates. Buying engineering, however, is not the same as controlling what it produces. A contract can deliver a report without the model behind it, a licence without the people able to interpret it, or access to a supplier network without any guarantee that the right specialists will be available when several programmes need them at once. The question that matters for European freedom of action is therefore not whether ministries and primes use external engineers, but under what conditions purchased engineering leaves a European customer able to understand, modify and sustain a military system after the original supplier, its personnel or its tools are no longer available.