27 problems carry too few suppliers

Everything needed to solve the problem exists — but one essential ingredient flows through a chokepoint. A special steel made by a handful of mills worldwide, rare earth processing concentrated in one country, an isotope only one facility produces. The risk isn't just price; it's strategic exposure: a single closure, dispute, or export ban stalls the whole field. Progress means finding substitutes, new sources, or designs that route around the chokepoint.