Anti-cruise missile missile
Anti-cruise missile missiles are a somewhat loosely defined category of weapons for missile defense. As opposed to the basic three stages of a ballistic missile trajectory, cruise missile flight paths are more variable. Intercepting a cruise missile that makes a high-altitude approach to the target area, perhaps dropping to low level for final approach, is a very different problem from intercepting a cruise missile in a terrain-following mode tens of meters above land or sea.
A significant portion of cruise missiles, but very few ballistic missiles, are launched from aircraft. With the maxim "it is better to shoot the archer than the arrow", some missiles, ostensibly anti-cruise missile missiles, actually are anti-cruise-missile-launcher-missiles. One of the first operational long-range air-to-air missiles (AAM), the AIM-54 Phoenix launched from U.S. Navy carrier-based F-14 Tomcat fighters, was intended for the "outer air battle". This doctrine combined long-range fighters and AAMs, with E2 Hawkeye radar aircraft, to try to shoot down the long-range aircraft of Soviet Naval Aircraft before they could fire their much faster anti-ship cruise missiles.
It reasonably can be wondered why, when the term anti-ballistic missile is widely accepted, this class of defensive weapon is not, in like manner, called an anti-cruise missile. No explanation is universally accepted. A technically coherent explanation is that "anti-ballistic" describes a particular set of intercept geometries against well-defined ballistic trajectories. Somewhat less coherent proponents of this school of thought suggest that "cruise", without "missile", requires disambiguation, lest a missile fired against a Raduga Kh-22 missile (Western designation AS-4 KITCHEN) might, instead, decide to attack the cruise ship SS Love Boat. Alternatively, without disambiguation, the anti-shipping version of the U.S. BGM-109 Tomahawk ASM might try to kill a rather harmless and obsolete Soviet Sverdlovsk-class cruiser.
Another school of thought is that a certain number of engineers managed to get away with the term anti-cruise missile missile, because no one, without a sense of humor, noticed before it was in the manual. It is believed that engineers of this school prefer to call decoys and other ballistic missile penetration aids, intended to foil anti-ballistic missiles, anti-anti-ballistic missile missiles. So far, the latter group has not done well.
Anti-cruise missiles for high-altitude intercept
While this was and is a real category, neither cruise missiles nor cruise missile carriers, which fly or are launched at high altitude, tend to fly other than a fairly straight course. Some, such as the Russian Raduga Kh-26, Western AS-6 KINGFISH, are very fast, but still a relatively straightforward intercept problem for an appropriate surface-to-air missile, such as the U.S. RIM-156 Standard SM-2 or the Russian naval variant of the Grushin S-300 (missile), the Altair S-300F Rif, Western SA-N-6 GRUMBLE.
U.S. Phoenix missiles were principally intended for use against the bombers, although they could intercept a straight-flying KITCHEN or KINGFISH. Extended-range versions of the AIM-120 AMRAAM are now being considered for a similar role, and it is possible the experimental NCADE missile may be adapted to this role.
Anti-cruise missiles for look-down shoot-down engagement
Killing a low-altitude cruise missile with an aircraft-launched missile is a more difficult problem, more of guidance than performance. Even if the missile is not explicitly stealthy, it is a difficult problem to discriminate a small target from radar reflections from land and water. Ground clutter from radar is one of the reasons that new long-range missiles such as the Novator R-172 and, if deployed against cruise missiles, the NCADE use infrared terminal guidance. Infrared tracking is generally short range, so radar may be needed to get the interceptor into the target area. The U.S. infrared Space Tracking and Surveillance System (STSS), while intended more against ballistic missiles, may be able to guide the interceptor close to the target.
Anti-cruise missiles for terminal defense
In the immediate area of the target, especially military one such as a warship, cruise missiles are apt to maneuver, possibly close to the surface or with a terminal pop-up maneuver both to confuse defenses and hit the target at a more deadly angle. As a result, gun systems, such as the Phalanx close-in weapons system, did not have the needed range and maneuverability to intercept.
Given the title of this article, it is just as well that Phalanx has been reassigned to land-based counter-rocket, artillery and mortar (C-RAM) duty, and replaced by the RIM-116 Rolling Airframe Missile. Otherwise, we would have to discuss anti-cruise missile guns, but the RIM-116 is indeed a missile missile.