Hypersonic missiles recently exploded into the news when China tested their own version of the WMD du jour.
Speed is just one of many ways to classify missiles: from the subsonic Tomahawk cruise missile flying 500mph to the ICBMs breaking free of earth's gravity at more than 15,000 mph. Hypersonic missiles fall in between at fives times the speed of sound around 4,000mph.
As with aircraft, speed is not the only measure of missiles. Intercontinental Ballistic Missiles (ICBMs) are very fast, but since ballistic means without power, they follow a very predictable parabolic flight/glide path to target. They accelerate to 15,000 mph to break free of the atmosphere, then coast over the the north pole to their final destination. The intercept path is very predictable.
At the other end of the scale, a Tomahawk (or other) subsonic cruise missile flies about the same speed as an airliner at around 500mph. They are very small, very light aircraft that are flown to their target. They can evade, maneuver and fly just feet above the ground and hit a target so accurately they can be flown into a particular car in parking lot.
Hypersonic missiles fly five times the speed of sound, in the range of 4,000 mph, in powered flight. They can fly high, low, maneuver, and evade just like a subsonic cruise missile, but fly from New York to Los Angeles in 45 minutes. Planes are very hard to shoot down. A hypersonic missile flies almost twice as fast as the Sidewinder air-to-air missile. It flies faster than the bullets from every US Army rifle and machine gun, faster than 30mm cannon rounds from the gatling gun on the A-10 Thunderbolt II ground attack fighter.
If China has operational hypersonic missiles, as recent news reports suggest, they could threaten other nations, including us, with dangerous, nuclear capable missiles.
If Taiwan becomes Crimea Part II, hypersonic missiles may be the threat that keeps America from defending a nation that has been very loyal to us. President Obama did nothing to stop Putin from seizing Crimea or invading eastern Ukraine. President Trump sold out the Kurds in Syria after one phone call from the Turkish President. Hypersonic missiles might seal the deal that puts Taiwan on the same path as Hong Kong.
Other entires in Field Guide to Flying Death:
And then there's the Sam Fender song, Hypersonic Missile