CDR McGeehan has served on both the CNO Strategic Studies Group and CNO Strategic Actions Group. This essay was submitted as a candidate in the Naval Submarine League Essay Contest while CDR McGee- han was a student at the Naval War College. –Ed.
Background
Since 1960, the U.S. Navy’s ballistic missile submarines (SSBNs) have been considered the most survivable leg of the nuclear tri- ad. While land based missiles are stationary, and nuclear capa-
ble bombers are tethered to airbases, the sea based strategic deterrent is highly mobile and continuously deployed, presenting major targeting challenges to adversaries. As 2/3 of the planet is covered by ocean and its average depth is approximately 2 ½ miles, SSBNs have room to ma- neuver, disappear, and remain hidden. Unlocated and untargeted, U.S. Navy SSBNs broadcast the message that America has a robust and sur- vivable second-strike capability. The capability is so trusted that SSBNs will soon carry nearly 70 percent of the U.S. strategic nuclear deterrent.i
Force structure planners have determined to make the massive in-vestment (over $97 billion) to recapitalize the SSBN component of the nuclear triad.ii As the new Columbia-class SSBNs will remain in service until 2080, it is imperative that this deterrent capability does in fact re- main credible well into the future. However, emerging technology and changing environmental conditions are conspiring to threaten the survivability of the future submarine force in general and SSBNs in particular.
Emerging Technology: UUVs
Unmanned Underwater Vehicles (UUVs) are rapidly gaining capability. Improvements in sensor packages, data fusion, and navigation systems, coupled with advances in onboard processing are enabling in- increasingly autonomous operations. Furthermore, improvements in power and propulsion to include more compact and reliable battery designs (like aluminum based batteries) are enabling significant gains in range and endurance, a critical enabler identified by the then Chief of Naval Operations (CNO), Admiral Greenert at the 2015 Naval Future Force Science and Technology Expo.iii UUVs are being employed in increasingly complex tactical operations, evidenced by the USS North Dakota, which performed the first launch and recovery of a UUV from a submarine during an operational mission in 2015.iv However significant they are in their own right, the tactical capabilities of UUVs will soon have even bigger, strategic implications.
Submarines continue to rely on stealth to protect them when de-ployed.v The vast three-dimensional sea-space available for submarines to maneuver is analogous to the air-space available to airplanes; hence, some lessons learned in one domain may apply to the other. In his 1921 treatise The Command of the Air, air power theorist Giulio Douhet wrote “destroying an enemy’s airplanes by seeking them out in the air is, while not entirely useless, the least effective method. A much better way is to destroy his airports.”vi Douhet argued that in an air war the advantage would lie with the attacker since he could attack from a range of approaches vice the defender who had to expend more resources searching a large volume just to find the attacker in the first place. Even if the defender did find the attacker he would have to be able to mass enough forces to effectively defeat the attacker, which is unlikely as his forces would likely be spread too thin during the search.vii
Applying this train of reasoning to the undersea realm, it is far easier to attack a submarine in port before it gets underway than it is to locate and engage one in the open ocean. In 2015, Russian state TV “leaked” details of a Russian Navy UUV that was essentially a long range nucle- ar torpedo designed to “destroy important economic installations of the enemy in coastal areas and cause guaranteed devastating damage to the country’s territory by creating wide areas of radioactive contamination, rendering them unusable for military, economic or other activity for a long time.”viii Such a weapon would be ideal for engaging an SSBN in port. However, while the weapon would impact that particular vessel,the base, and the supporting infrastructure (not to mention population), there is still the consideration that there is redundant capability with other SSBNs already underway, and therefore the sea based strategic deterrent remains viable. Just attacking the submarines in port alone would not suffice to cripple the overall capability; there would also need to be a complementary attack capability to neutralize the SSBNs already deployed.
A variation of the “attack while in port” strategy is to have UUVs continuously loiter in the vicinity of an SSBN port. These UUVs could be equipped with explosive payloads and triggers, essentially acting as mobile mines and “blockading” the SSBNs in port. Yet another variation is for those loitering UUVs to trail SSBNs as they got underway. With sufficient speed and endurance, a UUV could trail an SSBN for the duration of its patrol. Depending on size, the UUV could carry a weapon of its own or simply have a means to broadcast the SSBN location to its own forces that could come in for the kill if and when required. Such a capability would negate the advantage of SSBN stealth. While these UUV capabilities may sound far-fetched, a vignette in the DoD’s Unmanned Systems Integrated Roadmap FY2011-2036 describes a UUV that could tether itself to the submarine and periodically adjust the tether to glide to the surface to broadcast its position and receive new instructions.ix A related concept, DARPA’s AntiSubmarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) is an autonomous surface vessel that provides long-range (10,000 nautical miles at 12 knots) and long-endur- ance (months) for continuous tracking of submarines.x ACTUV is not just a concept; the prototype is in the water and was christened the “Sea Hunter” last year.xi
Other Emerging Technologies
With the introduction of the P-8A Poseidon maritime patrol aircraft, the U.S. Navy has led the way into high-altitude Anti-Submarine Warfare (ASW), which other nations are likely to follow (indeed, several other nations are already buying the P-8 itself).xii Operating well above the traditional operational height for maritime patrol aircraft, high-altitude ASW aircraft allow faster transits, greater range, and more time on station. Furthermore, operating at higher altitude allows aircraft to maintain line of sight contact to a more distributed sonobuoy field to hold more area at risk, especially when used in concert with other advances like Boeing’s High-Altitude Anti-Submarine Warfare Weapon Capability (HAAWC). The HAAWC program couples the Mk 54 torpedo with a steerable folding wing assembly that will allow the torpedo to be de- ployed from 30,000 feet and glide (with GPS navigation) to the desired impact point, vice the aircraft having to descend below 500 feet to de- ploy a torpedo directly overhead.xiii This capability will allow the P-8A to further increase its standoff range, as well as conserve fuel and time, again allowing it to remain on station longer. In the future, the HAAWC could even allow for dataupdates to refine the impact point as the torpedo glides through the air, further reducing the time and space available to the submarine to react and evade the torpedo. While these capabilities are valuable contributions to overall U.S. Navy ASW, it is only a matter of time before adversaries develop similar capabilities, which could be used to more efficiently target SSBNs.
In recent Congressional testimony, Bryan Clark of the Center for Strategic and Budgetary Assessments testified that other ASW technologies were proliferating, to include highly effective low-frequency active sonar. Furthermore, he described other potential advances in the development of non-acoustic ASW methods, such as employing “technologies that detect chemical or radiological emissions or bounce laser light off a submarine.”xiv In short, new technology is making it increasingly difficult for SSBNs to hide and remain hidden.
Changing Environment
In addition to emerging technology, changes in the environment itself may in some ways make SSBNs more vulnerable. Climate change has led to measurable changes in the physical properties of the ocean, which may impact underwater sound propagation, sonar effectiveness, and the ability of SSBNs to remain undetected.
Since the industrial revolution, rising levels of atmospheric carbon dioxide have led to increased oceanic uptake of carbon dioxide as it is absorbed by surface waters. This ultimately has led to the phenomenon of “ocean acidification.”xv On the global average, the ocean surface has already increased in acidity by 30% from pre-industrial times, and
is expected to double by 2100.xvi Low-frequency sound attenuation is a function of seawater pH.xvii As the ocean becomes more acidic the absorption of sound decreases, causing some frequencies to propagate slightly farther and therefore raising the chances of detection.xviii While this effect is small, in his Campaign Design, CNO Admiral Richardson reminds us that in today’s competitive security landscape “the margins of victory are razor thin – but decisive.”xix Any possible vulnerability to SSBNs, however small, must be considered.
Changes in the Arctic Ocean will continue to impact submarine operations, in particular those of potential adversaries. The Soviet and later Russian SSBNs leveraged Arctic sea ice to help form a protective bas- tion and increase their survivability. SSBNs loitered under the ice, ready to surface and launch if required.xx There was a high barrier to entry for under-ice submarine operations, which required unique capabilities like ice strengthening and sufficient buoyancy to break through thick pack ice. Now, as the ice cover recedes the submarines are more vulnerable to harassment from ASW aircraft and surface ships. Other physical changes in the Arctic Ocean include the emergence of the “Beaufort Lens.” This feature forms in the Beaufort Sea between warmed near-surface waters and a deeper warm layer entering the Arctic from the Bering Strait. Sound speed varies with temperature (as well as salinity and pressure), so sound refracts and becomes trapped between these two layers, leading to increased propagation ranges. Recent observations have shown acoustic propagation ranges four times as large as they were before emergence of the lens.xxi
Implications for Deterrence
The increasingly capable submarine detection methods and weapon systems led the then Commander, Submarine Forces Admiral Rich- ardson (now CNO) and Lieutenant Joel Holwitt to write in 2012 that “More than ever, it is easy to be “seen,” which can lead to being targeted and, increasingly, hit.”xxii This sentiment is disconcerting for submarines in general but even more alarming for SSBNs. Threats to SSBNs are by their nature destabilizing. Both sides knowing that the other has a credible second-strike capability adds stability. Any doubt as to the sur- vivability of the strategic nuclear deterrent could lower the threshold of their employment; SSBNs could be employed sooner in a crisis instead of as the ultimate last resort, if they become a capability that one must use or expect to lose.
However, these threats to submarines go beyond impacts on strategic deterrence; they impact conventional deterrence as well. Potential ad- versaries have acquired Anti-Access Area Denial capabilities (A2AD) in an effort to keep U.S. forces at an arm’s length and limit power projection capabilities. With A2AD systems presenting threats to surface forces, air forces, and forward bases, the submarine option has been considered a trump card that can penetrate A2AD zones and fight from the inside out. xxiii This conventional capability deters adversaries as it allows the U.S. Navy to hold their forces, lines of communication, seaborne commerce, and infrastructure at risk. Submarine access is an asymmetric advantage that features prominently in thinking about the Navy’s function of All Domain Access, and in the new Joint Concept for Access and Maneuver in the Global Commons (JAM-GC).xxiv
However, a reassessment of A2AD implications may be in order in light of the emerging technologies described here. While it is unlikely that adversaries will post surface ships directly off of our coasts, future UUV technologies in particular could allow clandestine means to challenge the U.S. Navy’s submarine access to contested spaces, and even their ability to put to sea in home waters. Just getting underway could be a challenge, and the entire transit to the battlespace could be contested.
Way Ahead: Counter-UUV Capabilities
Like an elephant harassed by a gnat, an SSBN would likely not be able to defend itself against UUVs. Therefore, counter-UUV capabilities will be critical enablers. However, with the size of the ocean battlespace the idea of individually hunting down particular UUVs or somehow seeking to engage them in a decisive Mahanian-style battle is impracti- cal. Instead, a more appropriate course to pursue would be what Sir Ju- lian Corbett described as temporary and local sea control, where one side would maintain superiority over an “operationally significant” region when necessary, which is essentially being able to accomplish missions at a time and place of one’s own choosing.xxv In this case that would mean securing the waterspace between the SSBN homeport and open water beyond, and only doing so as an SSBN was getting underway, vice trying to control the entire volume of a major piece of the ocean all of the time. This control is localized and fleeting; the SSBN just needs time to run the gauntlet to get to appropriate waterspace that allows sufficient room and conditions to disappear. To secure the submarine component of strategic deterrence, the Navy should consider investing in the following counter-UUV capabilities:
1) Port UUV detection and localization system. SSBN home- ports in particular will need enhanced undersea surveillance capabilities to detect the presence and location of UUVs. The previous analogy to Douhet’s air power theory showed that he was correct, but only to a point. He maintained that the advantage would lie with the attacker as the defender would have to search the entire volume of airspace to find the attacker, while the attacker could just focus on inflicting damage. However, this simplified model did not take into account the role of ad- advancing technology. During World War II, the newly developed RA-DAR system allowed the Royal Air Force to detect and vector limited fighter assets to intercept German bomber formations during the Battle of Britain. A similar undersea capability, coupled with the limiting lines of approach dictated by geography and bathymetry will confine adver- sary UUVs to smaller regions and make sanitizing and defending the waterspace much more manageable (which could be done with manned or unmanned platforms of our own).
2) Breakout capability. Borrowing a page from the mine warfare playbook, the Navy needs a capability to breakout from UUV infested ports. Routine bottom surveys with “change detect” algorithms will be required to counter UUVs that are “pre-staged” (possibly years in ad- vance analogous to DARPA’s Upward Falling Payloads) on the bottom and just waiting for commands that direct them into action.xxvi Sweep and neutralization functions will also be required to declare a transit lane officially sanitized (at least for the moment).
3) Decoys. Decoys (acoustic and otherwise) could be employed when SSBNs were getting underway to try and lure adversary UUVs away. These could also be deployed from the SSBN itself periodically while underway as a countermeasure for any trailing UUVs that it happened to pick up.
4) Delousing capability. In addition to decoys, the Navy needs to develop a “delousing” capability to deal with any trailing UUVs while underway. Whether this could be done during a rendezvous with a friendly ship, submarine, or swarm of friendly UUVs, the Navy needs an ad hoc mobile capability to use for SSBNs already on patrol. A fixed system (even deployed in a remote area) runs the same risks the SSBN faces getting underway from a port; adversary UUVs could just loiter in the vicinity of the “delousing station” and pick up the SSBN and trail after it departs the station.
5) Standoff counters. Just as it is more efficient to target an SSBN before it gets underway, some counter-UUV capabilities should apply before the UUVs are even on station. UUVs could be delivered via surface ships (military or civilian), submarines, larger UUVs, and aircraft, or be self-deploying and travel under their own power from distant bases. Better maritime domain awareness (MDA) and focused intelligence gathering will play an increasing role in tracking and interdicting possible delivery platforms.
Way Ahead: Counter-Transparency Capabilities
Better awareness of the ocean’s physical properties will allow SSBNs to avoid areas with conditions that support extended acoustic propagation and could betray their presence. The following capabilities should be considered for targeted investments:
1) Improved environmental sensing systems. Better sensing and sampling systems will increase real time awareness of changing ocean conditions. Both in situ (buoys, moorings, drifters, wave gliders, etc) and remote (satellite, aircraft, etc) sensing systems are required to assure the coverage and fidelity of observations.
2) Improved modeling capabilities. To fully exploit the environment the SSBN force will need predictive capabilities that allow its boats to avoid waterspace with conditions that favor the searching party. This drives the need for enhanced modeling capabilities with higher temporal and spatial resolution and longer lead-times. Furthermore, this will drive the need for enhanced computing capacity due to the increased computational cost, and necessitate more supercomputing power.
3) Improved Tactical Decision Aids. Forecasts alone are not enough. The SSBN force will require better tactical decision aids to reduce the cognitive load placed on commanders and decision makers to make sense of the environmental model output. Improved algorithms and decision aids will allow an SSBN crew to maximize the competitive advantage from the forecast environment, minimize the signatures they present, and manage their associated risks.
Way Ahead: Distribute the Deterrent Capability
The SSBN deterrent has historically also had numbers on its side (i.e. the capability was distributed across many platforms). Starting with “41 for freedom” back in 1959, the number of SSBNs has continually declined, through the Ohio-class that dropped to 16 boats and then 14 (with 2 repurposed as SSGNs), and to the new Columbia-class, which is planned to have 12 boats.xxvii The SSBN component of the nuclear triad is becoming increasingly consolidated on fewer and fewer boats. An intriguing idea is to distribute the submarine launched ballistic missile (SLBM) capability across multiple platforms, not just the SSBNs. Block V Virginiaclass submarines could be modified to carry the Trident SLBM within their Virginia Payload Modules (VPMs).xxviii The Navy is planning to acquire 20 Block V Virginia-class submarines. At less than half of a Columbia, pursuing this option could reduce pressure on Navy shipbuilding accounts as well. This would allow a more widely distributed deterrent and complicate any attempt to threaten the continuous at sea deterrence capability in general. However, it is recognized that incorporating Trident onboard other submarine classes is non-trivial. There are extensive burdens related to personnel reliability, enhanced security, assurance of nuclear command and control, the need for specialized storage magazines, and more intensive training.
That said, there is a case that those costs would be acceptable to achieve a counterpart of the Navy’s surface community “distributed le- thality”; this would be considered “distributed survivability.”
Conclusion
For almost 60 years SSBNs have been considered the most survivable leg of the nuclear triad. Emerging technology and environmental changes could pose future threats to that survivability. The Navy and the Nation must act now to ensure that the SSBN remains a credible and viable component of strategic deterrence in the 21st century.
Notes:
i Kreisher, O., Panelists Urge Investing in Upgrading Nuclear Deterrence Triad, Seapow- er, April 4, 2017, http://seapowermagazine.org/stories/20170404-panelist.html
ii O’Rourke, R., Navy Columbia Class (Ohio Replacement) Ballistic Missile Submarine (SSBN [X]) Program: Background and Issues for Congress, Congressional Research Service, April 4, 2017, https://fas.org/sgp/crs/weapons/R41129.pdf
iii Aluminum batteries could let submarine drones see further, The Economist, March 11, 2017, http://www.economist.com/news/science-and-technology/21718492-armed-forc- es-areamong-those-interest-aluminium-batteries-could-let ; Smalley, D., CNO: Here’s What We Need for the Future Force, Navy, February 5, 2015, http://www.navy.mil/sub- mit/display.asp?story_id=85464
iv Associated Press, Submarine launches undersea drone in a 1st for Navy, Military Times, July 20, 2015, http://www.militarytimes.com/story/military/tech/2015/07/20/ submarine-launchesundersea-drone-in-a-1st-for-navy/30442323/
v Jonathan Correa, Submarine Force Commander Welcomes Future Officers to Fleet, Navy, February 5, 2016, http://www.navy.mil/submit/display.asp?story_id=92985 vi Douhet, G. & Harahan, J. P. & Kohn, R. H. & Ferrari, D. & Harahan, J. P. & Kohn, R. H.. The Command of the Air. Tuscaloosa: The University of Alabama Press, 1998. Project MUSE, https://muse.jhu.edu/chapter/365900
vii Douhet, G., The Command of the Air, USAF Warrior Studies, 1942, https://archive. org/stream/dominiodellariae00unse/dominiodellariae00unse_djvu.txt
viii Russia reveals giant nuclear torpedo in state TV ‘leak’, BBC News, November 12, 2015, http://www.bbc.com/news/world-europe-34797252
ix Unmanned Systems Integrated Roadmap FY2011-2036, Department of Defense, 2011, http://www.acq.osd.mil/sts/docs/Unmanned%20Systems%20Integrated%20 Roadmap%20FY2011-2036.pdf x Littlefield, S., Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV), DARPA, http://www.darpa.mil/program/an- ti-submarine-warfare-continuous-trail-unmannedvessel
xi Pellerin, C., Work: Robot Warship Demonstrates Advances in Autonomy, Human-Machine Collaboration, DoD News Defense Media Activity, April 8, 2016, https://www. defense.gov/News/Article/Article/716156/work-robot-warship-demonstratesadvanc- es-in-autonomy-human-machine-collaboration
xii Norway has ordered five Boeing P-8A Poseidon, Norwegian Government Press Release, April 4, 2017, https://www.regjeringen.no/en/aktuelt/norge-har-inngatt-kon- trakt-om-kjop-av-femnye-p-8a-poseidon-maritime-patruljefly/id2546045/ ; U.S. Navy Awards Boeing $2.5 Billion Contract for 20 More P-8A Poseidon Aircraft, Boeing Press Release, January 29, 2016, http://boeing.mediaroom.com/2016-01-29-U-S-Navy-Awards-Boeing-2-5-Billion-Contract-for-20-More-P-8A-Poseidon-Aircraft
xiii Burgess, R., Navy Expects to Field Winged ASW Torpedo by 2020, Seapower,
March 29, 2017, http://seapowermagazine.org/stories/20170329-asw.html
xiv Clark, B., Game Changers- Undersea Warfare, Statement before the House Armed Services Subcommittee on Seapower and Projection Forces, October 27, 2015, http://csbaonline.org/research/publications/undersea-warfare-game-changers/publica- tion xv What is Ocean Acidification?, National Ocean Service, http://oceanservice.noaa. gov/facts/acidification.html
xvi Cooley, S., Mathis, J., and K. Yates, 20 Facts about Ocean Acidification, U.S. Ocean Carbon and Biogeochemistry Subcommittee on Ocean Acidification, April 2013, https:// www.iaea.org/ocean-acidification/download/OA20Facts_Nov.pdf
xvii Ilyina, T., Zeebe, R., and P. Brewer, Changes in underwater sound propagation caused by ocean acidification, Climate Change: Global Risks, Challenges and Decisions, 2009, http://iopscience.iop.org/article/10.1088/1755-1307/6/46/462007/pdf
xviii Ilyina, T., Zeebe, R., and P. Brewer, Changes in underwater sound propagation caused by ocean acidification, Climate Change: Global Risks, Challenges and Decisions, 2009, http://iopscience.iop.org/article/10.1088/1755-1307/6/46/462007/pdf
xix A Design for Maintaining Maritime Superiority, Navy, January 2016, http://www.navy.mil/cno/docs/cno_stg.pdf
xx Kraska, J., Arctic Security in an Age of Climate Change, 2011, https://books.google.com/books?id=b-U1To97zqsC&pg=PA93&lpg=PA93&dq=rus- sia+bastion+ssbn+arctc&source=bl&ots=ILB7xUlxSS& sig=zqHNmeDqNKL-ARC_ rNRCFgFCubo&hl=en&sa=X&ved=0ahUKEwiO-93R4J3TAhVX42MKHVTG-
C8wQ6AEIKjAB#v=onepage&q=russia%20bastion%20ssbn%20arctc&f= false
xxi Warming spurs new 400km undersea sound channel in Arctic, Acoustic Ecology Institute, January 23, 2017, http://aeinews.org/archives/3188 ; Smalley, D.,
Cold Front: ONR Researchers Explore Arctic Land and Sea at Navy ICEX, Office of
Naval Research Press Release, March 30, 2016.
xxii Richardson, J. and J. Holwitt, Preparing for Today’s Undersea Warfare, USNI Pro- ceedings, June 2012, https://www.usni.org/magazines/proceedings/2012-06/prepar- ing-todays-underseawarfare
xxiii Richardson, J. and J. Holwitt, Preparing for Today’s Undersea Warfare, USNI Proceedings, June 2012, https://www.usni.org/magazines/proceedings/2012-06/prepar- ing-todays-underseawarfare
xxiv A Cooperative Strategy for 21st Century Seapower, Navy, March 2015, http://www.navy.mil/local/maritime/150227-CS21R-Final.pdf; Hutchens, M., Dries, W., Perdew, J., Bryant, V., and K. Moores, Joint Concept for Access and Maneuver in the Global Commons: A New Joint Operational Concept, Joint Forces Quarterly, January 27, 2017, http://ndupress.ndu.edu/Media/News/Article/1038867/joint-concept-for-access- andmaneuver-in-the-global-commons-a-new-joint-operati/
xxv Vego, M., Joint Operational Warfare: Theory and Practice, 2009, https://books.google.com/books?id=zUP23aBHLOwC&pg=SL252-PA51&lpg=SL- 252PA51&dq=corbett+local+sea+control&source=bl&ots=l-kw2KN9L_&sig=n-JMG3GiFepLFswt_dbm4u9C9-ZM&hl=en&sa=X&ved=0ahUKEwis4fk953TAhX- HjlQKHdfrCwEQ6AEISDAF#v=onepage&q=corbett%20local%20sea%20 control&f=false
xxvi Upward Falling Payloads Advances Deep-Sea Payload Technology, DARPA Press Release, March 26, 2014, http://www.darpa.mil/news-events/2014-03-26
xxvii Richard, C., Validating Sea Based Strategic Deterrence, Navy, http://navylive.dod- live.mil/2016/03/17/validating-sea-based-strategic-deterrence/
xxviii Ilteris, S., Build Strategic Fast Attack Submarines, USNI Proceedings, October, 2016, https://www.usni.org/magazines/proceedings/2016-10/build-strategic-fast-at- tack-submarines
