The concentration of production of rare earth elements (REEs) outside the United States raises the important issue of supply vulnerability. REEs are used for new energy technologies and national security applications. Some Members of Congress have expressed concern over U.S. acquisition of rare earth materials composed of rare earth elements used in various components of defence weapon systems. These elements are referred to as "rare" because although relatively abundant in total quantity, they appear in low concentrations in the earth's crust and extraction and processing is both difficult and costly. China's position as the world's dominant producer and supplier of rare earths and its policies to limit exports have raised concerns among many in Congress. This book examines the economic and trade implications of China's rare earth policies for the United States. Other topics, separately explore the use of rare earth elements by the Department of Defense and end use markets.