The U.S. Army's version of the Navy's CIWS Phalanx anti-missile system is called the "Land-Based Phalanx Weapon System" (LPWS). It is a type of "C-RAM" (counter-rockets, artillery and mortars) defensive weapon.
Whereas naval Phalanx systems fire depleted uranium or (more recently) tungsten armor-piercing rounds, the LPWS uses the HEIT-SD (High-Explosive Incendiary Tracer, Self-Destruct) ammunition originally developed for the M163 Vulcan air-defense system. These rounds explode on impact with the target, or upon tracer burnout. With a reliability of between 95 and 99 percent the odds of live rounds falling on "friendlies" is minimal.
Don't want to be a bore but please stop discussing the technical detail of this system on this site. There are thousands of servicemen relying on it to save their lives on a daily basis. They don't need you lot to openly discuss its capabilities or specification.
I thought matelots were maintaining it, if not operating it, as they're the ones who've been using the system for the last 25 years. Probably not a bad system for what the Army are using it for - against a supersonic sea skimmer I'd prefer Goalkeeper.