Base Hardening

We’ve discussed the vulnerabilities of our forward bases (see, "Base Defense") and, among other actions, noted that we should be pursuing hardening of our bases.

National Interest website makes the point that hardening includes far more than merely protecting the aircraft on the ground.

“However, protecting the aircraft is just a first step. Combat aircraft sortie generation can be thought of as an industrial process with the airfield as a “sortie factory.” The factory needs working aircraft, but the aircraft must be able to taxi to a runway that is long enough for them to operate from safely and when they return they must be able to be repaired, refueled and rearmed, and their crews must be able to receive orders and plan missions. This means other parts of the factory must be protected if the base is to function under attack. This means hardening maintenance, fuel storage and distribution and operations facilities.” (1)

This is an interesting, and correct, take on the issue that recognizes what an airbase actually is and, therefore, the scope of what must be protected.  This leads to the concept of a “sortie chain”, similar to a kill chain, in which a series of steps are required to generate a sortie.  Breaking the chain at any point will terminate the sortie.  For example, there is no need to destroy the aircraft if you can destroy the fueling facilities or the maintenance facilities or any other step in the chain - hence, the need to harden the entire chain and its associated facilities.

Dr. Carlo Kopp notes that China is actively pursuing airbase hardening and presents data on the extent of that effort.

“The only nation in the region actively investing in airbase hardening over the past decade is China, which has incrementally expanded its inventory of underground hangars (UGH), while investing in HAS [Hardened Aircraft Shelter] at multiple airfields.

China’s tally as of 12 months ago (http://www.ausairpower.net/APA-2011-01.html) was 7 x UGH sized for Badger bombers, capable of accommodating 138 – 145 aircraft (or many more fighters), 14 x UGH sized for Beagle bombers, capable of accommodating up to 668 Flankers, 17 x UGH sized for MiGs, capable of accommodating up to 723 J-10 fighters, for a total of 38 sites, with several further sites unused or abandoned. In addition, all other PLA fighter airfields are equipped with revetted dispersals, and a good number have been upgraded with HAS.” (2)

Dr. Kopp also makes the point that China’s huge advantage in hardened sites creates a strategic imbalance in their favor.  The side that is better prepared to absorb attacks and continue to fight has a significant advantage – no great surprise but a concept seemingly lost on Western military professionals.

Air Force Magazine website notes some of China’s HAS efforts.

“Distributed over 15 air bases throughout Nanjing and Guangzhou military regions in the east and southeast of China, the number of hardened shelters has grown from 92 to 312 in the past 12 years …” (3)

Hardened aircraft shelters (HAS) are not a magic solution to attack and do not grant immunity to damage.  Precision guided, penetrating bombs will destroy HAS structures as the US demonstrated during Desert Storm and, just recently, in the Tomahawk attack on the Syrian airbase associated with chemical weapons.  What HAS (and any form of hardening) does is to eliminate the cheap kills and drive up the cost of achieving the desired degree of destruction.  “Dumb” bombs are plentiful - precision guided, deep penetrating bombs are not.  

Kopp illustrates the point using the Desert Storm war.

“When Coalition air forces flew into Iraq in early 1991, they confronted the most extensively hardened airbase system ever built. Saddam’s hardened airbases proved ineffective, and Coalition tactical fighters destroyed 375 of 594 during the six week air campaign. With complete control of the air won within the first day, Coalition fighters were able to repeatedly attack HAS installations until they were cracked open. The pivotal weapon used was the American 2,000 lb BLU-109/B I-2000 Have Void concrete piercing bomb, fitted with either the GBU-10, GBU-24 or GBU-27 laser guidance kit. Typically two weapons were used per target, the intent being for the second round to punch into the hole made by the first round. While many HAS were punctured in an initial attack, many others required repeat attacks until fatal damage was inflicted. This absorbed a significant proportion of available Coalition sorties, as the limited number of F-111, Tornado, and Buccaneer aircraft equipped to laser illuminate targets set hard limits on daily sortie rates.” (2)

Hardening did not defeat the overall attack but it greatly increased the time and effort required for the Coalition to achieve its goal.  The key lesson is that many hardened targets required multiple re-attacks.  In Desert Storm, with total control of the air, we were able to re-attack as often as needed.  Against a peer adversary and lacking control of the sky, the ability to knock out hardened bases becomes a much more difficult and questionable task and re-attacks will likely be prohibitively expensive, in terms of attacking aircraft attrition or simply not possible given sortie availability and defense changes.

A related point is that the type of laser guided, precision, penetrating bombs used by the US require that the launching aircraft (and lasing aircraft, if they are not the same) overfly or very closely approach the target.  Again, against a peer with a credible SAM system, this may be costly or impossible.

Kopp also discusses underground hangars.

“The alternative to HAS, underground hangars, if built with proper entrance designs, deflection grids and blockers, can resist repeat attacks with tactical fighter compatible concrete piercing bombs. Such targets require genuine ‘earthquake bombs’, such as the new 30,000 lb GBU-57/B Massive Ordnance Penetrator (MOP)…” (2)

Air Force Magazine notes possible vulnerabilities of underground hangars.

“… the perceived vulnerability of UGHs to precision weapons. Most of the shelters have only a few entrances, which if struck could pin aircraft inside for an extended period. …

Precision strikes against the taxiways leading to the entrances could also hinder operations. Although aircraft inside may survive, it could prove difficult to extract them from their underground lair and launch. In addition, it might be possible for the first precision guided munition to penetrate the doors with a follow-on weapon to detonate inside the UGH.”

Just as there is a crowd of people who believe that since armor can’t stop every weapon that exists, there is no point having any armor, so too there is a crowd, likely the same crowd, who believes that since no amount of hardening can stop every bomb or missile, there is no point hardening bases.  Clearly, this is misguided, idiotic thinking.  Hardening (or armor, as the case may be) drastically drives up the cost and effort for the attacker.  In a peer war, where you may only get one chance at an attack, hardening ensures that at least some of your assets survive and forces the attacker to expend many more assets than would otherwise be required.  China recognizes this and is preparing their bases accordingly.

On the U.S. side,

“Currently, the US military has 207 HAS dispersed among four bases in the Western Pacific, with a significant majority in South Korea.” (3)

On the other hand, some key U.S. bases have little in the way of hardening.

“Kadena Air Base on Okinawa, located just 460 miles from the Taiwan Strait, houses F-15s and occasionally F-22s—and large numbers of other USAF aircraft—but possesses only 15 shelters.

Andersen Air Force Base on Guam hosts a range of strategic assets, such as B-2 stealth bombers and RQ-4 surveillance aircraft, but has no hardened shelters.” [emphasis added] (3)

The US needs to devote serious efforts towards hardening its few forward bases.  This is a key point since the US has so few forward bases in the Pacific – Guam being the notable example.  We need to do all we can to ensure that Guam can withstand attack and continue to function.  

Can we afford more hardening efforts?  From Air Force Magazine,

“… it should be noted that roughly 20 new hardened shelters can be purchased for the cost of a single fourth generation fighter.” (3)

On the opposite side of the coin, we need to devote more effort to figuring out how to more efficiently and safely destroy hardened facilities.

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(1)National Interest website, “Base Hardening: Can America and Its Allies "Play Fort" against China?”, Harry J. Kazianis, October 27, 2014,

http://nationalinterest.org/feature/base-hardening-can-america-its-allies-play-fort-against-11551

(2)“Airbase Hardening in the Western Pacific”, Dr. Carlo Kopp

http://www.ausairpower.net/PDF-A/DT-Hardening-Mar-2012.pdf

(3)Air Force Magazine website, “The Dragon Pours Concrete”, David Lewton, Dec 2014,

http://www.airforcemag.com/MagazineArchive/Pages/2014/December%202014/The-Dragon-Pours-Concrete.aspx