20 January 2007

Shashou Jiang: Ballistic Missiles vs. CSGs (Pt II)

The phrase "assassin's mace" is the English translation of "shashou jiang," a term of ancient Chinese strategy. "Shashou jiang" was a club with which the "assassin" incapacitated his enemy, suddenly and totally, instead of fighting him according to "the rules."

To summarize from Part I – a Chinese strike using Theater BM’s has been conducted against two American CSGs enroute to the Taiwan Straits as a show of US resolve and support to Taiwan during another brewing cross straits crisis. The strikes garnered mixed results, with the loss of two support ships and minor damage to a few destroyers in the GW CSG and extensive damage to the Reagan – akin to what the Enterprise had suffered some fifty years earlier following a major flight deck fire. Most of her embarked airwing is damaged or destroyed except for some assets that had been struck below to the hangar bay. Loss of life, while not insignificant, is on the order of 150 killed, 210 wounded (many with burns) and several, mostly form the two auxiliaries still missing at sea. In addition to the losses at sea, shore-based aircraft at Okinawa and Guam also suffered losses with the brunt being borne by the Navy’s shore-based ASW assets. Less than 1/3 are considered flyable and at Kadena, much of the infrastructure (fuel, maintenance facilities, etc.) has been disrupted. Two squadrons of F-22B Raptors, flown in for offensive counter air operations and a Marine F/A-18C Hornet squadron similarly suffered losses. On orbit, the US early warning/launch detection satellite system has also been degraded although with time and repositioning of assets, the impact will not be as keenly felt as the losses closer to the surface.


In scenario play, it’s easy to make the enemy’s weapons always lethal, remove/reduce gaps in intelligence and every decision is on time and the right one. Conversely, one can also make every defensive countermeasure 100% successful too... In view of that concern, just how plausible is this scenario? A simple model using Terminal Kill Potential (TKP) follows. TKP is the determination of the military threat potential of a weapons systems and is found through the following equations:

The Pk of any system is a function of the multiplication of the probability of success of each of its subcomponents -- the more subcomponents and the more challenging flight environment, the lower the Pk will be. Even assuming an overly optimistic 99.9% probability of success for countdown (c), launch (l), flight and re-entry (f), guidance (g) and warhead reliability (w), the OAR for this system yields a 99.5% reliability unopposed – add an ABM system (1-PA ) that is only 75% reliable and the OAR plummets to 25%. Assuming a nuclear warhead (for which this calculus was derived) with a small yield (150 KT) and a CEP of 3000 yds, the SSKP = 1.0 (assuming a “soft” target – overpressure of 3.6 psi to kill) and yields a TKP of .995 (unopposed) or .248 (vs. an ABM system).(1) With conventional, chemical or biological warheads TKP would face further challenges (active seeker reliability, dispersion of submunitions, etc). The number of variables that can be injected are mind-numbing, everything from impact of weather to LO or ‘stealth’ measures taken by the target to something as seemingly mundane as a back-up generator that has a history of injecting power surges prior to shutting itself down – all have an impact on the reliability and hence, the probability of kill by a system. TKP can be substantially enhanced by employment of large numbers of conventionally armed missiles.

As laid out above, there are many hurdles the Chinese would have to overcome to effectively conduct anti-CSG strikes with shore-based TBMs. Consider the target – the CVN’s at the core of the CSG. Critics of big-deck carriers regularly make reference to their inherent size and hence, alleged ease to target. True enough, in benign conditions and with a cooperative target, carriers can be readily located and targeted. This becomes an especially problematic issue if a carrier has to operate close to shore or in restrictive waters as it narrows the range of possibilities the opponent must consider in setting up a search plan.

In the above scenario you had two different situations – one CSG in relatively open ocean, proceeding in a formation that provides for mutual support, but widely dispersed owing to networked sensors and communications. This CSG has the sea room, coupled with advance warning to complicate the target acquisition phase in the terminal stages of the TBM strike. Consider – a modern CVN can make in excess of 25 knots. Big deal you say? 25 knots is what, 28 – 29 mph? What does that buy? It means in one hour the carrier has moved 25 nautical miles from its starting point. Yes, but the time of flight of a ballistic missile (in this scenario) is about 20 minutes, you reply. At 25 knots, a carrier will cover roughly 800+ yards every minute – 8 football fields per minute. In 20 minutes it will have moved 16,000 yards or 8 nm. There is enough error induced such that a non-maneuvering, conventional RV could conceivably miss wide of the mark, especially if a course change is cross range (perpendicular) to the ballistic missile’s path. Remember, once launched there is a minimal amount of maneuver a ballistic missile may engage in – the target coordinates will generally not be updated and it will likely end up delivering its payload to open ocean.

A MaRV improves the probability of a strike though. With a terminal detection capability (radar, IR, anti-radiation) that error may be reduced – if the target is detected in enough time in the terminal phase. Generally speaking, one can expect a MaRV to be flying at about Mach 8 endoatmospherically. Owing to the construct of the RV, payload weight penalties, speed and thermal effects, the terminal seeker will necessarily have a limited field of view. If the target falls outside the field of view, the warhead subsequently has a PK of 0, especially if it is a unitary device. If the target does fall in the Filed of View (FoV), there still may be aerodynamic limits on the RV’s ability to maneuver. There are two options to reduce the impact of targeting uncertainty in this scenario – use “smart” submunitions or go nuclear. The latter, particularly in an airburst mode, would be effective up to certain ranges/yields. To a country looking to terminate another’s course of action while minimizing the possibility of escalation though, nuclear weapons are generally not the first round of choice. Smart submunitions, on the other hand, have proved themselves effective against a variety of soft and semi-hardened targets under actual combat conditions for some time now. By 2015, the technology involved in miniaturization of submunition seekers should promote the use of a variety of sensor types to be carried in one RV payload as well as the number of submunitions.

Open ocean surveillance is platform- and time intensive. Substantial resources can and usually are spent in this endeavor. A threat that goes unlocated ramps that effort up even more – just ask the Soviets about efforts to find a CVBG in the North Atlantic that is making every effort to ensure that is as difficult a problem as possible. Using EMCON, deception, even weather to its advantage, CVBGs (which counted substantially more ships than CSGs today) could go unlocated for days at end while remaining in range to conduct long-range strikes. To offset that advantage, a series of platforms and tactics are used to establish a layered defense with platforms re-enforcing one another. For instance – OTH-R can and has demonstrated an ability to locate and track a carrier-sized target. It, however, can not discriminate between a carrier and a similarly sized crude oil carrier, especially if one is trying to locate a CVN which is using a busy sealane to mask its presence. Of course, that advantage could be offset via tattle reporting from a passing vessel owned by or sympathetic with the Chinese.

Similarly, on the defensive side challenges abound. A kinetic kill vehicle-based missile defense would be challenged in several areas. Target cuing, tracking, reporting, acquisition and intercept would provide several avenues of approach for counter-measures. Balloon decoys, chaff, jamming – all the penetration aids presently used on strategic missiles would be employed in an attack launched by MR/IRBMs. Using different radar types and frequencies helps sort through the decoys to uncover the warhead.

So what is the plausibility of the above? Is China pursuing such technologies as part of its defense restructuring. In a word, yes. Reading the latest defense White Paper published by the PRC, one will not see explicit reference to pursuing these measures. Rather, look to their actions instead – lasing of US satellites, tests with MaRV warheads, purchase of OTH-R from Russia, network intrusions and attacks and now an operational ASAT test. In the coming year we will expand further – not just on weapons and tactics, but on the strategy and politics that could either precipitate or diffuse confrontation.)

(1) For reference, a 2 MT single warhead ICBM has a .67 TKP against a hardened Minuteman silo.