Invincible East Wind 東風?
Exploring countermeasures to China's "Carrier Killer" DF-26
The People’s Republic of China stakes claim to almost the entirety of the South China Sea (SCS). Their Nine-Dash Line – sometimes also referred to as the Ten-Dash Line and the Eleven-Dash Line – demarcates the Chinese claim to a large portion of the SCS at the expense of every one of its neighbours. It is pursuing its claims aggressively, formalising control by setting up administrative entities for disputed islands and underwater structures, threatening its weaker neighbours with the use of raw power, and using coercive non-military power to ensure submission of disputants.
But its control over the SCS is hotly disputed. Legally by neighbours like Vietnam, and militarily by the United States Navy (USN) which insists on frequently sailing its Carrier Strike Groups (CSGs) at will through those international waters to make it clear that Chinese control over the SCS is, for the moment, nominal. China has been seeking the ability to deny unhindered passage to the USN, and believes it has found it with the Dong Feng series of ballistic missiles, specifically the DF-21D and the DF-26.
East Wind
The DF-21 is a medium-range solid propellant ballistic missile believed to have a range of 2,150km, capable of carrying a nuclear or conventional warhead weighing 600kg. The DF-21D, called a carrier killer, is a conventionally armed variant of the DF-21 that has been designed to attack ships at sea. The CSIS Missile Defence Project reports that its range is 1,450km to 1,550km, and it has a Circular Error Probability (CEP) of 20m.
The DF-26 is a longer ranged version of the DF-21 capable of striking targets 4,000km away. It is a two-stage missile with an estimated CEP between 150-450m.
Launched from China’s Hunan province, the DF-21D covers about half the SCS. The DF-26 covers it entirely, and brings Guam into range.
Both are billed as carrier killers, and China’s propaganda arms have, on more than one occasion, publicly touted these missiles as threats aimed squarely at the USN. A recent public back and forth between the Global Times and the USN’s Chief of Information was especially ‘spicy’. GT claimed that the carrier killers gave China the ability to regulate movement in the SCS.
The USN responded that the USS Nimitz and the USS Ronald Reagan are not intimidated.
How would such a carrier killer ballistic missile work?
Well, it cannot be a dumb ballistic missile. Let’s take the example of a DF-26 launched at the USS Nimitz at the edge of its operating envelope. Assuming performance similar to other IRBMs, the DF-26 takes 25-35 minutes to travel 4,000km. Let’s say it outperforms others and takes 20 minutes.
The launch will be detected by the Defence Support Program, the Space-Based Infrared System, and the Space Tracking and Surveillance System. These systems consist of satellites in Geosynchronous Earth Orbit (GEO) and Low Earth Orbits (LEO) that use sensors to detect infrared emissions from the intense heat generated during the launch and boost phase of ballistic missiles.
Let’s allow 5 minutes for detection and communication to the USS Nimitz, because we’re in a generous mood and want to give the Chinese a fighting chance. The USS Nimitz is capable of making 31.5 knots or 58.3 kmph, and now has 15 minutes till impact. That allows the Captain of the Nimitz to move 14.57km away. If the DF-26 were a dumb ballistic missile, the Captain would just change course, use maximum power, and put 20-30 km between the ship and the point where the DF-26 would impact.
The Chinese aren’t dumb
Their carrier killer won’t be a dumb ballistic missile either. I discussed this with the non-corporeal sentient entity known as Firestarter (@Firezstarter1 on Twitter), and here’s how it went. I mentioned the scenario modelled above.
FS: I suspect they have some way to provide data to the IRBM making it a MaRV. So basically, it's not going for a fixed place but actively trajectory shaping.
And Wikipedia bears him out. The DF-21D (and consequently the DF-26 too) employ Manoeuvrable Re-entry Vehicles (MaRVs) with a terminal guidance system.
The Maneuverable Re-entry Vehicle (abbreviated MARV or MaRV) is a type of ballistic missile whose warhead is capable of autonomously tracking ground targets. It often requires some terminal active homing guidance (like Pershing II active radar homing) to make sure the missile does not miss the target, because of the frequent trajectory shifts. [Wikipedia]
The Jianbing-5/YaoGan-1 and Jianbing-6/YaoGan-2 satellites are believed to offer targeting information from radar and visual imaging respectively [YaoGan-1 is reported to have broken up from an internal explosion on 4th February 2010, but we’ll continue using that name under the assumption that the Chinese are using another SAR satellite like YaoGan-1 for targeting and guidance].
SA: The terminal guidance system cannot be infrared. It won’t work after re-entry.
FS: Yes, the plasma formed after re-entry would interfere with an IR sensor. But other forms of active guidance, like the radar on the Pershing II, cannot be ignored.
At this point Firestarter pointed me to a lovely article on Arms Control Wonk (ACW) that discusses potential guidance systems for the DF-21D. ACW explores the possibility that it uses an IR sensor up to the point when it re-enters the atmosphere at an altitude of 50km. That leaves 22 seconds to impact. So if the missile gets a final lock on the Nimitz 22 seconds before impact, the Nimitz could travel about 360m before impact. If the missile has extrapolated correctly, and its control systems work as expected, there’s a decent probability that the carrier is severely damaged.
But there are always caveats and complications
Add to this mix the strong possibility that it continues receiving updates from the two satellites mentioned before – Jianbing-5/YaoGan-1 and Jianbing-6/YaoGan-2 – even after its IR sensor has ceased functioning, and you have a fairly potent weapons system.
FS: What if it can accommodate cluster munitions? PGMs that have their own IR sensors? Basically, don’t launch one DF-21D / DF-26. Launch a dozen, each with 6 PGMs. That way the Nimitz has to dodge 72 PGMs, improving the probability of mission-killing or damaging it.
SA: Six PGMs would weigh 300kg each. Explosives would be around 100kg in each because they’ll need guidance systems, aerodynamic surfaces and their actuators, etc. for manoeuvrability. A 100kg warhead might damage the carrier, but won’t destroy it unless they hit it just right. A mk48 torpedo has a 300kg warhead. And it can kill a carrier IF it explodes beneath the keel. PGMs cannot use that approach to kill the carrier.
FS: Yes, definitely not destroy it. At best damage, or Mission Kill it. The entire kill chain is too complex. You can, however, slow down the missile via MaRV to optimize it for cluster munitions.
Then I decided to try my hand at being Captain of the Nimitz. Results were as expected.
SA: Say I’m Captain. I get a warning - 15 mins to impact. I tell the CSG to flee in random directions. Full speed. I launch a dozen aircraft. They fly all around me and launch chaff. They use their radar jammers. As the missile approaches apogee, they deploy a fuckton of flares. Your missile guidance system has to navigate all that crap and find me, then manoeuvre at Mach 8 to hit my deck dead centre. That chaff interferes with SAR as well. As do the jammers of my aircraft.
FS: No, you don't do all that, it will delay you.
SA: Is your guidance computer fast enough and powerful enough to cut through all that noise at Mach 8?
FS: Just manoeuvre.
SA: That’s also a possibility. But I’d feel safer with a tonne of chaff around me. Maybe chaff shells that my destroyers shoot off into the sky. All while I’m manoeuvring like mad.
FS: Chaff needs to be timed.
SA: I know which direction it’s coming from, so I manoeuvre perpendicular to it.
FS: You want it above you and besides you. So, it gets a bit risky. To launch aircraft, you need to be into the wind. So best you jam and run. Use chaff, flares. I would rather split the formation and zig zag instead of wasting time to launch aircraft.
At this point I realised that were I at the helm of the Nimitz we wouldn't make it far. Master & Commander I am not. Therefore I put the scenario to Firestarter.
SA: Let me put this scenario to you. You’re Captain Firestarter, captain of the USS Nimitz sailing 500km east of Taiwan. You’ve been informed that a DF-26 has been launched at you. What do you do?
FS: I first use my deployed fighter, E2C screen to take out any ISR aircraft shadowing me. Second, I manoeuvre away from the projected location to the max possible extent. I keep active measures, passive measures limited and am on EMCON (Emissions Control – basically, radio silence). I don't want anyone to know where I am at all. Passive, receive only data linking, SATCOM. I deploy my E2C, fighters off axis to further screen my formation. So, I sprint but with a focus on ensuring my zig zag does not take me in a predictable linear trajectory which falls w/in salvo limits.
SA: But won’t passive measures have only a limited effect, especially if they’ve fired a salvo of 5-6 missiles. You have to blind the guidance system, and that means jamming YaoGan-1, YaoGan-2, and the active seeker in the missiles themselves. We’re talking power budgets less than 10 kW for the entire satellite which includes the Synthetic Aperture Radar (SAR) for YaoGan-1 and the optical systems for YaoGan-2.
FS: Worth exploring. Let’s start with the YaoGan-2, which has an optical sensor which, we would assume, looks well into the IR end of the spectrum. In what kind of weather conditions does this scenario take place?
SA: We are going to assume this happens in the middle of a bright and sunny day with not a cloud in sight.
FS: The obvious defeat would be for the entire CSG to begin generating visual and infrared screening smoke the moment a DF-26 launch is detected & communicated to it. That should hide it from YaoGan-2. It will also serve to jam the IR seeker on board the DF-26 (if the DF-26 does have an IR seeker) and, consequently, result in the guidance computer falling back on YaoGan-1’s SAR since, at this point, the missile won’t be close enough to the Nimitz to use its in-built radar (assuming it has that too).
The CSG will have to jam the SAR on YaoGan-1. The ships in the CSG will have chaff for protection against RF-guided anti-ship missiles. In addition, the real-time location of YaoGan-2 is available via civilian resources like N2YO, and it isn’t absurd to assume that the US Space Force, which is also responsible for missile warning, will have an accurate fix on it. Deception jamming of the SAR onboard YaoGan-1 might be possible for the CSG given an accurate fix on the YaoGan-1’s position, resulting in YaoGan-1 being ‘shown’ a target where none exists. But there are gaps like the absence of a ‘system of systems’, identified by AFCEA among others as far back as 2016, that prevent the CSG from leveraging the EW assets of the entire CSG in a coordinated manner against a threat like the DF-26.
While jamming the YaoGan-1 & 2, the same time, the Aegis Ballistic Missile Defence System would also be utilised to shoot down the missile. The RIM-174 Standard Extended Range Active Missile (ERAM) also known as the SM-6 is an endo-atmospheric interceptor which uses a blast-fragmentation warhead to intercept, among other things, ballistic missiles in the terminal phase. It has a stated range of 370 kilometres. The USN plans to purchase 1,800 of these missiles and, as of 2015, more than 180 had been delivered.
SA: If I were Captain, I’d pop off those SM-6 like it was Diwali as soon as their targeting systems tell me I can. The DF-26 is receiving guidance from SATCOM. Is SATCOM agile enough to guide it through a gauntlet of SAMs travelling at Mach 3.5? Just the latency of Observation by Satellite -> Transmission to Earth -> Processing -> Transmission back to Satellite - > Transmission to DF-26 should make that very difficult. And even if SATCOM somehow manages to do that without the DF-26 veering way off course, can it manoeuvre with the agility required to defeat SAMs?
FS: Arms Control Wonk mentions two possibilities for the DF-26's manoeuvring: Thrusters or Aerodynamic Surfaces. If it’s the latter, they won’t work well until the missile has descended to about 30km above the earth’s surface. The SM-6’s operational ceiling is 34km, so the DF-26 can very well be intercepted before its aerodynamic surfaces are fully operational. If it’s Thrusters, a gauntlet of SAMs will cause the DF-26 – if it is capable of evasive manoeuvres – to expend precious fuel that may be needed for terminal manoeuvres. And each evasion will cause it to deviate from its targeted path.
SA: So the DF-26 isn’t an impossible-to-defeat weapons system.
FS: I agree. It isn’t impossible-to-defeat. But it will be hairy for the CSG, especially since the Chinese will swarm them with multiple missiles and they lack a system-of-systems to coordinate EW systems across ships in the CSG.
Payload über alles!
But an important factor is the payload the DF-26 would be carrying. A conventional warhead would require precise targeting – or as close to it as the missile can achieve. What about a nuclear warhead? The Dong Feng-4 carries a 3.3 Megaton warhead. Simulating that warhead with surface burst yields the following:
Strong probability of a Mission Kill up to 6.82km from a surface burst of a 3.3MT thermonuclear explosion.
In the absence of clear knowledge of the kind of payload the DF-26 carries, the CSG would certainly unload its inventory of SM-6s, deploy all sorts of countermeasures, and sail hell for leather to get out of the missile’s way.
Another countermeasure available to the US is to destroy YaoGan-1 and YaoGan-2 with the RIM-161 Standard Missile 3 (SM-3), crippling the guidance system for the missiles. The satellites are in orbit at an altitude of ~650km. The SM-3 Block IIA has a flight ceiling of 1,500km and an Operational Range of 2,500km.
A satellite at altitude 650km would lose line of sight to a ship behind the horizon if it were more than 2,950km away assuming, as I must, that the ship is of negligible height. So the Chinese could, theoretically, manoeuvre the satellites to an orbit just beyond the range of the CSG’s SM-3 Block IIAs. But a satellite in such an orbit would be well in range for SM-3s stationed, hypothetically, at Okinawa, Japan.
Could China manoeuvre its satellites into an orbit that avoids both the SM-3s in the CSG as well as the SM-3s in Okinawa? Perhaps. Would such manoeuvring go unnoticed at US Space Force? Unlikely.
It doesn’t appear to be a fire-and-forget scenario for China at the moment.
Shaunak Agarkhedkar writes spy novels. His first two - Let Bhutto Eat Grass & Let Bhutto Eat Grass: Part 2 - deal with nuclear weapons espionage in 1970s India, Pakistan, and Europe.
Firestarter is a state of mind.