From the Summary: "Congress has expressed interest in cruise missile defense for years. Cruise missiles (CMs) are essentially unmanned attack aircraft -- vehicles composed of an airframe, propulsion system, guidance system, and weapons payload. They may possess highly complex navigation and targeting systems and thus have the capability to sustain low, terrain-hugging flight paths as well as strike with great accuracy. CMs can be launched from numerous platforms -- air-, land-, or sea-based -- and they can be outfitted with either conventional weapons or weapons of mass destruction (WMD). The Department of Defense is pursuing several initiatives that seek to improve capabilities against an unpredictable cruise missile threat. This report will be updated as events warrant."
CRS Report for Congress, RS21921