That's what Task & Purpose calls the recently revealed R9X version of the Hellfire missile. The Wall Street Journal described it thus:
The U.S. government has developed a specially designed, secret missile for pinpoint airstrikes that kill terrorist leaders with no explosion, drastically reducing damage and minimizing the chances of civilian casualties, multiple current and former U.S. officials said.
. . .
A modified version of the well-known Hellfire missile, the weapon carries an inert warhead. Instead of exploding, it is designed to plunge more than 100 pounds of metal through the tops of cars and buildings to kill its target without harming individuals and property close by.
To the targeted person, it is as if a speeding anvil fell from the sky, the officials said. But this variant of the Hellfire missile, designated as the R9X, also comes equipped with a different kind of payload: a halo of six long blades that are stowed inside and then deploy through the skin of the missile seconds before impact, shredding anything in its tracks.
There's more at the link (behind a paywall, unfortunately).
As Task & Purpose discovered, there may already be photographic evidence of its effects. Nick Waters provided these images via Twitter, showing the car in which Abu Khayr al-Masri, deputy leader of Al-Qaeda, was assassinated in Syria in 2017.
Video of the vehicle, showing recovery efforts, may be found here. It certainly makes it look as if it was difficult to extract those inside, possible testimony to the striking power of the missile and its blades.
The red lines in the images above indicate straight-line cuts in the vehicle around the missile entry point. Mr. Waters also showed this conceptual image of how the blades might deploy around the missile in the split-second before impact. (The missile's electronics presumably measure how far it is from its target, and release the blades just in time to cause maximum damage, but before they can disrupt the weapon's flight path.)
I'm familiar with simple kinetic weapons such as the USA's Lazy Dog bomb containing metal darts. Rhodesia developed something similar under "Project Hotel", described as basically 6-inch nails fitted with plastic tail fins, scattered from improvised containers beneath an aircraft's wings. They proved very effective in bush warfare, but were only used to a limited extent. This approach, using a blade-equipped but otherwise inert Hellfire missile, is something new. Given its velocity of over Mach 1, I imagine that even a glancing blow from one of them would prove lethally effective, while being much more precise than a scatter-shot area weapon.
A collection of swords, moving at 1,000 mph . . . shiver! Remind me to stay far away from them!