Krugman cites the near monopoly of rare earth materials by China, and the embargo on export to Japan, as an irresponsible exercize of economic power by China. These materials are used in many high-tech devices.The monopoly itself was a result of the US neglecting its production of these materials in the US. In one case, he says, the US allowed the Chinese to literally pack up all the equpment of a US factory and ship it to China. Low wages and lax environmental standards helped China to price below the U.S. industry, leading to its shutdown.