Dr. Lowell (CAPT (Ret.)) is a 30-year submariner with operational and acquisition assignments in five SSBNs (including command of USS BENJAMIN FRANKLIN BLUE and GOLD) and program manager positions in NAVSEA and DARPA. Since retiring from the Navy in 1997. he has worked advanced technology development projects at Electric Boal Corporation including participation on the Missile Defense National Team.
The U.S. should develop and deploy a submarine-based ballistic missile defense capability that could operate close to potential threats without political provocation or risk of attack. Such a capability would impose costs on potential adversaries, increase their risk of operational failure, and bolster U.S. regional security alliances.
The Threat- Ballistic missile (BM) threats against the U.S. homeland and regionally against allies, partners and their deployed forces are becoming more flexible, mobile, survivable, reliable, and accurate, with increasing range. Continued evolution by Iran and North Korea of BMs towards intercontinental BM (ICBM) ranges and repeated demonstrations of salvo launches enabling large attack raid sizes must both be considered in U.S.’s fielding a BM defense system.
Currently, against limited potential ICBM threats to the homeland, the U.S. has fielded a midcourse defense capability – consisting of ground-based interceptors at Ft. Greely, Alaska and Vandenberg Air Force Base, California; land-, sea- and space based sensors; and a global command and control, ballistic missile and communications (C2BMC) network. Alternatively, in the future with very high speed regional interceptors, a Defense Science Board study concluded that forward-based advanced regional interceptors against hostile ICBMs on trajectories towards the U.S. could significantly improve homeland ballistic missile defense (BMD) using a “shoot-assess-shoot” concept. Meanwhile, against the rapidly proliferating regional threats from short and medium-range BMs (SRBMs and MRBMs), the U.S. is maturing a flexible BMD capability called the phase adaptive approach (PAA). PAA addresses land-based point defense using Patriot Missile batteries and area defense using Terminal High Altitude Area Defense (THAAD) and Aegis Ashore, in addition to deployable sensors for detecting and tracking ballistic missiles (e.g., ANffPY-2 X Band Radars). However, the sea-based Aegis BMD system using Standard Missile (SM) variant interceptors are the centerpieces of this system.
The Sea-Based Advantage – Sea-based platforms are sovereign U.S. assets that can exploit the in-theater maneuver space without host country permission. That flexibility and proximity to potential adversaries they can achieve, makes sea-based BMD ideal for boost-/early-ascent phase intercepts (before missile countermeasure deployment) or mid-course geometries. They can position mobile sensor platforms for tracking and classifying adversary missiles, augmenting land-based and space-based systems. In addition, they complement ongoing initiatives for regional collaborations with evolving NA TO sea- and land-based BMD capability.
For these reasons, plus the availability and maturity of Aegis BMD, the U.S. selected an evolutionary four-phase PAA, using a combination of re-locatable land and sea-based systems. PAA is a more cost effective system relative to a large, fixed land-based footprint and minimizes political entanglements. A 2009 review concluded PAA was the best method for addressing the regional Iranian BMD threat in Europe. In 2011, the U.S. Missile Defense Agency (MDA) implemented Phase I, Initial Integrated Defense, and achieved initial operational capability against SRBMs, MRBMs and intermediate-range BMs (IRBMs). This phase uses sea-based Aegis BMD and SM-3 Block IA interceptors. Evolution to Phase 4, Early Intercept and Regional ICBM Defense should complete by 2020 with airborne sensors (ABIR) or sensors in orbit (PTSS) to detect and track hostile missiles, advanced discrimination technologies, advanced Aegis BMD capability (afloat and ashore), higher velocity SM-3 IIA/B interceptor missiles, and enhanced C2BMC to intercept large raids of MRBMs/IRBMs and non-advanced ICBMs early in flight.
The Submarine Advantage – Submarines could provide a complementary capability in the European Phased Adaptive Approach (EPAA) or in other theaters. By exploiting the large payload volume available in SSGNs or future VIRGINIA-class attack submarines (SSNs) equipped with payload modules, these submarines could conduct near simultaneous intercepts against recently launched hostile missiles (defensive capability) and strike missions (e.g., tomahawk) against launch complexes/platforms (strike capability).
Submarines could covertly, independently, persistently patrol in optimal operating areas – sweet spots to maximize defended area, early battle space intercepts and shoot-assess-shoot engagement opportunities – fulfilling two BMDS axioms: (1) Geography counts, and (2) The farther forward you attack, the more advantageous it is. Surface combatants similarly located could be subject to harassment or attack. Submarine-based BMD can offer non-provocative, survivable presence in a readiness posture analogous to that of an alert SSBN. Although interceptor launches could temporarily disclose a submarine’s location, submarine crews are adept at quickly recovering their stealth.
Submarines deploying with the SM-3 Block IIA could provide an engage on remote capability to complement other PAA components. This concept was validated in April 2011 when USS O’KANE (DOG 77) used an in-service SM-3 Block IA for a launch on remote intercept of a modified Trident I/C-4 ballistic missile target based on non-organic detection and tracking data inputs.
Significant payload capacity exists today in four SSGNs. However, these ships will retire without replacement in about 18 years. In order to maintain undersea payload capacity, the Navy is considering the insertion of payload modules into future VIRGINIA-class SSNs. VIRGINIA Payload Modules (VPMs) would provide additional missile stows that could carry BMD interceptors, strike weapons, or unmanned vehicles. This added payload capacity could accommodate more energetic interceptors to engage longer-range threats and provide greater defended area protection to the U.S. and its allies. Overall, the Navy’s BMD capability would increase with more sea-based launchers and a greater depth of magazine.
Study Recommends A Submarine BMD Solution – In 2007 a joint Navy-Missile Defense Agency team conducted an alternatives assessment to differentiate between sea-mobile platforms capable of hosting the kinetic energy interceptor (KEI) system. KEI was a large, highly energetic missile planned for boost phase intercept missions. Although the KEI program was eventually cancelled, conclusions from the assessment remain relevant to new, more capable ballistic missile interceptors such as the SM-3 Block IIB.
The KEI study assessed boost, ascent, and mid-course intercept concepts. For boost- and ascent-phase missions, converted SSBN (SSXN – retired from Trident mission and transferred to KEI mission only) was the launch platform of choice… although it could be augmented by the SSGN for Increased flexibility and firepower. For mid-course intercept, SSXN was again the preferred platform, but an optimally designed commercial containership could provide almost equal benefit at potentially less cost. Platforms considered included back fit installation on SSGN, retired SSBN, DDG-51 Flight JIA, LPD-17, a T-AKE support ship, and a new-build commercial containership. Other platforms considered but not examined included CG(X), CG-47, DDG-1000, tug-barges, oil platforms, SSNs and other older Navy combatants and amphibious ships. Multi-mission SSBNs carrying both KEI and Trident II DS missiles were dismissed due to policy considerations. SSGN was retained for consideration due to its relative ease of missile integration and covert operational capabilities. VIRGINIA-class attack submarines with large diameter payload tubes were not conceptualized, and therefore were not considered as alternatives.
These conclusions were based on a weighted-attribute, cost benefit assessment and comparison of platform options. Costs included up-front development, testing, procurement, operating and support considerations. Benefits included a combination of differences in performance (BMD capability, survivability, and availability), platform suitability (development and fielding schedule, raid handling capacity, KEI component growth margin, human system factors, integration, and endurance), risk (technical, operational, programmatic, and schedule) and Navy force structure impacts (opportunity cost of performing KEI mission and other logistical support requirements, defensive escort requirements).
Technical and Operational Feasibility – To alleviate concerns about a submarine’s ability to perform the BMD mission, the study focused on high-risk areas of submarine timelines for boost phase intercept and general communications concerns with integration and operation. For the submarine conducting boost and ascent-phase intercepts, the study answered two main questions: ( 1) could the boost-phase timeline be met, and (2) was the predicted availability of submarine systems sufficient to execute the KEI mission. The timeline issue was simply whether communications concepts existed (or could be developed) to ensure receipt of a conditional alert and launch command on board, and whether pre-launch operations could be conducted on the submarine within the required timeline. Submarine communications options that were investigated concluded that communications could meet the KEI requirement- to include boost-phase timelines. For the stringent boost-phase timelines, changes to the very low frequency (VLF) system were investigated and proposed by Space and Naval Warfare Command (SPAWAR). SPAWAR concluded that VLF would permit sufficient information to be transmitted to and received by the submarine to allow for KEI launch. Satellite communications (SATCOM) options were deemed viable backup paths for boost phase for cases when the submarine was at periscope depth (PD) and were also deemed viable to support much larger data rates for the midcourse mission.
Onboard pre-launch operations were also investigated to ensure the submarine could meet a reasonable boost-phase launch timeline. For the availability question, several issues were considered: (I) whether there exist wash-over or platform motion issues with the mast/buoy/wire antenna that would substantially limit communications availability, and (2) whether platform control in high seas would substantially limit system availability. The study assumed that for boost- and ascent-phase intercepts, KEI in-flight communication (KICS) and fire control functionality (KFC) would be performed off-board the submarine ashore or aboard a surface ship. That concept now embraced as engage 011 remote is scheduled to be fielded as phase 3 EPAA capability.
Midcourse considerations assessed the same timeline and system availability constraints. The study identified no critical showstoppers.
But that was then, and this is now. Since the study, several Submarine Force initiatives have improved the flexibility with which a submarine BMDS capability can be deployed.
- SSGNs, initially deploying in October 2007 with USS OHIO, launched multiple tomahawk cruise missiles from a single 7-pack Multiple All up Round Canister (MAC) in a missile tube. (KEI study assumed a single interceptor per tube.) Given that SM-3 missile variants are of comparable size to a tomahawk, a significant interceptor battery could be covertly stationed in theater to engage large raids.
- Two large diameter OHIO-like missile tubes are being built into the VIRGINIA Class submarine (Block 3) bow,
with designs to insert a 4-tube VIRGINIA Payload Modules (VPM) in follow on VIRGINIA Block 5. This capability will increase the payload capabilities when SSGNs are retired.
- As an alternative to encapsulated missiles, such as stealthy affordable capsule system (SACS) examined in the study, the Water Piercing Missile Launcher (WPML) could enable launch of a non-marinized missile without encapsulation costs and post-launch debris fall out concerns for the submarine. The study envisioned (for a mid-course KEI intercept) the ability to erect a large diameter antenna on a retractable mast from a missile tube if required. Deployed at PD following a bell-ringer early warning issued by the BMDS C2BMC, this antenna would provide tracking and communications with the hostile missile/interceptor. The ability to erect/retract such large payloads from a missile tube has been demonstrated on the Universal Launch and Recovery Module.
Submarine BMD Operational Concepts – Submarines conducting BMD missions would operate similarly to an SSBN on patrol. Commanders would adopt operating profiles (speed, depth, launch/fire control equipment readiness, proximity to potentially hostile surface contacts, etc.) within acceptable limits determined by the necessary response time. Without special communications antennas, the submarine would engage on remote with cues and external (post-launch) control by other platforms and systems tracking the threat missile(s) and tracking and communicating with the interceptor.
The submarine assigned to a BMD mission would operate in an alert readiness condition. It would be in continuous (receive only) communications listening for an alerting message indicating the possibility of a hostile ballistic missile launch. Upon receipt of that message, the submarine would acknowledge receipt using a towed or expendable communications buoy with transmit capability; state the submarine’s readiness to launch; and specify its geographic position. It would then transition to maximum readiness posture and stand-by for a launch order.
If the alert is evaluated to be legitimate (i.e., a hostile launch), and the submarine is selected as the platform optimally positioned to engage the threat missile(s), the submarine would receive a launch order with fire control parameters (e.g., state vector) calculated for the interceptor to engage the threat missile. This message would pass through submarine communication systems directly to the fire control and launch systems. With the submarine operating within acceptable launch parameters, launch would proceed automatically (aborted by ship’s operators only by exception). The submarine would continue launching until its salvo is complete (i.e., all released interceptors deployed, hostile missiles out of range, etc.). Corrected intercept calculations and interceptor redirection would be performed by other off-board sensors/communications systems consistent with the PAA engage on remote concept.
With interceptor launches complete or if the submarine is not directed to launch, it maneuvers to clear datum to regain operational stealth at best speed/depth and reconfigures ship’s systems consistent with maintaining required readiness levels, including maintaining continuous communications as required. The submarine could also be directed to preemptively strike other hostile missile assets or command and control facilities.
Submarine Ballistic Missile Defense Is A Cost Imposing Strategy – Adding new payloads like SM-3 variants to submarines increases their capability and imposes cost on potential adversaries. They would have to presume interceptor-equipped submarines were operating in theater and capable of intercepting missiles launched against the U.S., its deployed forces, or against regional security partners. Submarines equipped with strike weapons (e.g., tomahawk cruise missiles) could conduct counterbattery strikes or preemptively strike other hostile weapons or support systems. If potential adversaries wanted to neutralize submarine-based BMD, they would have to increase missile capabilities (velocity at burnout, deployment of countermeasures, etc.) and/or inventories significantly, or develop a credible antisubmarine warfare (ASW) force. Both options are expensive, with the latter being operationally challenging- requiring high technology platforms and highly skilled operators.
Because of its unique operational attributes, submarines could complement the established Aegis BMD-centric PAA with access to areas hazardous to non-stealthy sea-based platforms. Submarines have established themselves as credible, combat tested missile shooters. If armed with appropriate interceptors, they could deter aggressors, or if necessary, defeat even large hostile raids. Submarine operational responsiveness demonstrated for other missions and increased emphasis on fielding middle ware to quickly accommodate non-marinized payloads, continue to validate the KEI alternatives assessment conclusion that “Overall, because the submarine already launches missiles larger than KEI, the submarine integration is minor compared with some of the structural changes associated with a surface ship.” Submarines could make an outstanding contribution to U.S. BMD efforts as an element of the current PAA.