Actually, they were first used as a deterant for terrorists in the Kingdom of Hawai'i. When one of these "warning shots" hit the ocean off the coast of Owahu, it released so much energy from the impact that it actually sparked lightning off of the water. These things don't even have warheads, they would be redundent. All they need is mass and velocity and they hit with the power of a meteor strike. You could, literally, blast a target off the face of the planet.
And the scary part of this is that the tech is very, very simple. The US government could have them floating up there right now and it is not only within the realm of possebility, would be a bit stupid if they didn't have these. A projectile that hits with the force of a meteor, leaves no fallout, can be guided in with fins, a retrorocket, and GPS transmitter, and is CHEAP. Hell, I'm surprised we even develpoed the MOAD at all.
Gabriel