News Analysis Talk 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? At the most basic level, 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. Hypersonic weapons currently come in two main varieties: hypersonic intercontinental ballistic missiles (ICBMs) and hypersonic glide vehicles (HGVs). Hypersonic ICBMs are simply ultra-fast missiles that are powered by rockets or other jets throughout their flight. They fly in ballistic trajectories, steeply arcing out of the atmosphere before returning to earth …