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A while back, Japan and China got in a tussle about sea rights. Japan took a Chinese trawler that was in its territorial water and held the Captain. Quietly, China blockaded shipments of "rare earth" materials to Japan. (Story) This means Japan couldn't build all kinds of things, like cell phones, electric car batteries. All kinds of high tech things.
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Now, the US used to be the primary supplier of this, but China undercut us. A case of where no trade barriers screwed us. In fact China companies so undercut us (or the U.S.) that these Chinese companies (owned often by their army) purchased our foundries, took them apart and shipped them to China to rebuild. Using much laxer laws to extract minerals, and cheaper labor to produce them, we gave up these industries in the name of market capitalism. Worse, American (and Australian and other) companies do the Chinese government's dirty work to maintain their access to the minerals.
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Cut to this week. China is pissed off at us (the U.S. and Europe) because we keep pushing on their undervalued currency. So they have cut off deliveries of these rare earth materials to us. Story.
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We are screwed because China doesn't play by Open Market rules and we have little leverage. What are these "non-critical" things we can't make? Lasers, Wind Turbines, Car Batteries, Solar Panels, etc.