Fast, low-flying cruise missiles attacking
targets on land or at sea are a very difficult threat against which to defend.
In principle, engagements of an incoming cruise missile far away from the
threatened target are highly desirable, because such engagements allow
multiple attempts to destroy the cruise missile. (An important collateral
benefit is that the long-range destruction of a cruise missile carrying
chemical or biological weapons reduces the likelihood that the chemical or
biological weapons agent will affect the target.)
Cruise missiles can be engaged with
surface-to-air missiles or fighters. In the case of a surface-to-air missile
engagement, the range at which it occurs is limited by one of two factors--the
fly-out range of the missile itself and the range of the sensors (usually
radar) that guide it to the target. However, the range of a ground-based radar
is limited by the line of sight to the horizon, which is typically much
smaller than the missile's fly-out range.
The horizon line-of-sight limitation can
be overcome by increasing the altitude of the radar (e.g., placing it on an
airborne platform) and thus increasing the radar line-of-sight range to the
horizon, or by using over-the-horizon sensors to guide the missile. It is
often the case that over-the-horizon sensors are present, but in general these
sensors will be associated with platforms other than the one that can fire the
In any event, a network of sensors
providing the right kinds of data can in principle support surface-to-air
missile engagements for any surface-to-air missile within fly-out range of its
target. Since fly-out ranges are often four to five times the distance to the
radar horizon, the improvement in air defense coverage is significant.
Today, the ability to employ networks of
heterogeneous sensors is limited by the fact that fire-control-quality data
cannot in general be shared among all the shooters that might come into play
in an engagement. Moreover, the "stovepipe" architecture in place can prevent
even the surveillance data generated by some sensors from being available to
certain shooters. The Navy's program to develop the Cooperative Engagement
Capability system is intended to provide such functionality for air defense
over water; similar developments are under way to provide comparable
capabilities over land.
SOURCES: Adapted from Joint C4ISR Decision Support Center. 1997. Precision Engagement C4I Operational Architecture Study (Sensor-to-Shooter III), Joint C4ISR Decision Support Center, Office of the Assistant Secretary of Defense for Command, Control, Communications, and Intelligence, Department of Defense, Washington, D.C.