Experiences in Operation Iraqi Freedom demonstrated that even conventional cruise missiles with limited reach could have disruptive tactical effects, in the hands of a determined enemy. Meanwhile, the proliferation of cruise missiles and associated components, combined with a falling technology curve for biological, chemical, or even nuclear agents, is creating longer-term hazards on a whole new scale. Intelligence agencies and analysts believe that the threat of U.S. cities coming under cruise missile attack from ships off the coast is real, and evolving.
Aerial sensors are the best defense against low-flying cruise missiles, because they offer far better detection and tracking range than ground-based systems. The bad news is that keeping planes in the air all the time is very expensive, and so are the aircraft themselves. As cruise missile defense becomes a more prominent political issue, the primary challenge becomes the development of a reliable, affordable, long-flying, look-down platform. One that can detect, track and identify incoming missiles, then support over-the-horizon engagements in a timely manner. The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor (JLENS) certainly looked like that system, but the Pentagon has decided to end it.