Ding Dong, Dong-Feng!

posted at 9:12 pm on August 7, 2010 by J.E. Dyer
[ National Defense ]   

Allahpundit laid down the gauntlet with this question on China’s new anti-carrier weapon, the Dong Feng-21D ballistic missile:

Exit question for military (preferably naval) readers: Big trouble here or overblown?

Answer from this naval reader:  both.  Perhaps “overblown” isn’t the right expression, so much as “blown by rogue winds and widely misunderstood.”  Allow me to explain.

The DF-21D isn’t a weapon we have no defenses against.  In fact, the US Navy’s Standard Missile (anti-air missile) program and ballistic missile defense (BMD) upgrade to the Aegis tracking and guidance system are the right defenses to deal with it.

Much is frequently made of how fast the DF-21D would be approaching its target in the terminal phase, but the gee-whiz aspect of that is overblown:  it’s a ballistic missile.  Of course it comes down really fast at the end.  That’s what they do.  The US has been working on ballistic missile defenses, afloat and ashore, for nearly 30 years now; the speed at which they plummet toward the earth is not a surprise.

We have also proven our ability to intercept ballistic missiles coming down at high speeds from extra-atmospheric apogees – although here our success has been slow, and proven mainly in controlled test conditions.  Almost all of the just-above-50% success rate has been achieved in the last decade (looking only at the last decade’s testing, the success rate is more like 80%).

That said, a ballistic missile coming down at a carrier is a different and faster-moving problem than an anti-ship cruise missile coming at a carrier.  Most of the cruise missiles out there (which fly like airplanes) are subsonic, and therefore relatively easy to shoot down.  The supersonic Russian-designed SS-N-22 Sunburn (or MKB Raduga) missile is an exception, and China does have that missile, as a weapon system on Sovremenny-class destroyers purchased from Russia.  (I note that cruise missiles aren’t the best weapon to use against a carrier anyway; they’ll be more likely to be used against escort ships and merchants.)

But the geometry of the ballistic missile problem is in a class of its own.  That’s what makes the DF-21D a potential game-changer:  the fact that the geometry of the problem, and the defensive tactics it would require, impose significant operational constraints.

Let me open that discussion with the observation that the fundamental significance of any of this will depend heavily on how effective the DF-21D’s terminal guidance is.  Unless China wants to just lob warheads out there to plop harmlessly in the ocean, the DF-21D will have to have a form or forms of effective terminal guidance.  Ships are moving targets, and for a ballistic missile, close will mean no cigar.  The DF-21D will reportedly have multiple independent reentry vehicles (MIRVs), unquestionably complicating the defensive picture, but the likelihood of any individual hit will be extremely low without hard-to-evade guidance.  There’s a good discussion on that here; the hardest guidance to evade is infrared (IR) homing, followed by radar homing.

Supposing China can make the DF-21D home on targets  to a level 50% as good as “perfect,” and supposing our own missile defenses function better with each passing year, we have a difficult but bounded problem.  And the big problem is not that we can’t defend our carriers at all, it’s that defending them would levy so many constraints on our operations.  In effect, the DF-21D is a harassment weapon, and a darn good one, if it works as it’s intended to.

Our carriers don’t carry ballistic missile defenses, for starters.  The Aegis ships – cruisers and destroyers – would have to defend them.  To some extent we already operate that way; a carrier is virtually never without an Aegis escort when it’s deployed forward.  But one is generally deemed enough; against enemy attack aircraft or cruise missiles, the carrier’s own defenses are effective and will catch close-in threats that slip through the Aegis net.  The carrier can defend itself from air threats with its fighter aircraft and short-range anti-air missiles – but these aren’t defenses against ballistic missiles.

If China can launch a barrage of MIRVed DF-21Ds, she can bog us down defending the carrier – or simply push us further offshore.  But the further offshore we have to operate, the more vulnerable our carriers’ aircraft are when they are approaching targets on land.  It’s not just the distance over which China has a shot at them, it’s that plus the fact that they will have to refuel in-air to get to the target and then back to “Mom” (the carrier).

The threat of a DF-21D barrage would also be a fouling agent for carrier flight operations.  The most vulnerable time of all is when aircraft are being recovered at the end of a mission cycle.  The Chinese know that.  Naturally, they will time DF-21D salvos to coincide with recovery ops.  When you’re trying to bring down 16 or 20 jet aircraft safely, you can’t keep changing course and speed and turning your electronics on and off.  The carrier has to be a safe recovery platform for her aircraft, otherwise there’s no point – and that’s the highest-payoff vulnerability for an enemy to go after.

If the DF-21D is mainly a nuisance, these issues can be addressed in the medium term with tactics, while we look for longer-term fixes in technology.  But the DF-21D will be only one of the disruptions a naval force faces.  It’s probably not going to be a very effective way to literally “kill” a carrier for some years to come.  A submarine nailing the carrier at the keel is a much better bet:  take out propulsion, you take out the whole weapon system.  Without propulsion, the carrier can’t make the 35 knots of wind over the deck that it needs to recover aircraft.  And China has lots of submarines.

It’s the combination of weapons China can increasingly bring to bear that the US Navy is worried about.  If we’ve got one big, honking set of tactical constraints imposed by the Chinese submarine threat, another posed by the Chinese attack aircraft threat, and another posed by supersonic anti-ship cruise missiles, adding the DF-21D as a flight-ops harassment problem makes it that much harder for our forces to keep their heads above water:  to use our weapons to actually attack the enemy, rather than just to defend ourselves.

(And yes, George and Meredith Friedman, authors of The Future of War, called this prospect for our carriers “senility,” and predicted it in theory, if not because of the particular threat posed by the DF-21D, back in the mid-1990s.)

Blowback