In the mid-2010s, Pentagon officials in the United States were alarmed by the military progress China and Russia were making. Both countries were investing in cyber, space, and electronic warfare capabilities as well as precision-guided munitions and long-range, ground-based weapons. U.S. Deputy Secretary of Defense Robert Work was particularly concerned about China, which he determined was trying to achieve parity with the United States in military technology. China had developed the DF-21D,