News AnalysisTalk of a new arms race between the United States and China has rapidly increased since a recent report by the Financial Times asserted that China had tested a nuclear-capable hypersonic weapon.But what are hypersonic weapons? How do they work? Who has them? And why does it matter?What are Hypersonic Weapons?Technically, hypersonic weapons are missiles that travel faster than five times the speed of sound, or Mach 5. This speed is roughly 3,800 miles per hour, but fluctuates with the object, altitude, and temperature, as these interact with the physics of sound.But speed is not the key defining feature...