Robotics deep dive: HUMANOID CHOKEPOINTS Almost every supply-chain post about humanoids has one country in it. Trace five critical inputs one at a time and they land in four different places. Magnets first, because that is where the argument usually stops. Every high-torque joint runs on sintered NdFeB, and on the IEA's 2024 figures China holds 91% of refined output and 94% of sintered permanent magnets, against 60% of the mining. Mining is the distributed part, and the chokepoint is the chemistry. The precision reducer is the node almost nobody names. Nabtesco states on its own site that it holds approximately 60% of the global market for the precision reduction gears in industrial robot joints. Harmonic Drive Systems is the incumbent on the strain-wave side. Both Japanese, both sitting on decades of gear grinding, heat treatment and yield that nobody has replicated at price. There is no mine to open here. Optimus runs 14 linear actuators; per-robot screw counts get estimated anywhere from 14 to more than 40, at $1,350 to $2,700 each. A planetary roller screw is a micron-tolerance ground part, and only a handful of firms anywhere make them to that standard: Japanese, German, Swiss, with Chinese entrants scaling into it now. The constraint is grinding capacity and the people who can run it. Compute inverts the picture. Nvidia designs Jetson Thor in California and cannot manufacture it. Roughly 92% of the world's sub-10nm logic capacity sits on one island. Battery cells go back to China: over 80% of global cell capacity, about 99% of LFP. A McKinsey component map, reported by Forbes in June, puts it the same way: China is overwhelmingly dominant in exactly one category, magnets for motors, while bearings, driver boards and sensors have suppliers in several countries. So it is four dependencies, held by parties with different export regimes, different politics and no shared interest in coordinating. A supply chain with one chokepoint is one negotiation. Reshoring the magnets still leaves you asking Japan for the gearboxes and Taiwan for the brain.