In June 2025 Sheffield Forgemasters, a forge owned by the United Kingdom’s Ministry of Defence, saw its recapitalisation plan raised from £900 million to £1.3 billion. Two weeks earlier Framatome had opened public consultation on Forge+, a new forge at Le Creusot, in the Bourgogne-Franche-Comté region, that it costs at €579 million. Both projects add the same industrial ability: turning very large steel ingots into the shells, plates and pipework that make up the primary circuit of a nuclear reactor. Both also serve more than one customer. The British forge describes its role in terms of the submarine and warhead programmes, yet it also supplies civil nuclear and offshore energy customers. The new French forge would be justified chiefly by orders for new EPR2 power reactors, yet the existing plant at Le Creusot is, in its operator’s words, the only French manufacturer able to produce the blanks for the nuclear propulsion plant of submarines and the aircraft carrier. For European rearmament that overlap is the point. In both countries naval nuclear propulsion draws on plants whose expansion is tied to civil as well as defence demand, and neither company publishes how much of the capacity it has, or will have, is already committed. The question is whether the heavy-forging capacity being added at Sheffield and Le Creusot can serve European defence demand when civil nuclear programmes drive and condition much of that expansion, and which instruments allow governments to impose priority on it.