UNITED STATES - NOVEMBER 10: Jeremy Siegel, the Russell E. Palmer Professor of Finance at the Wharton School, addresses the Securities Industry Association during their annual meeting in Boca Raton, Florida, Thursday, November 10, 2005. Matt Stroshane | Bloomberg | Getty ImagesChina’s control over crucial rare earth materials has been a “threat for a long time” to Western supply chains and the U.S. should create a strategic reserve of the metals, University of Pennsylvania professor emeritus of ...