The Use of Land-Based Air Defenses to Screen Sea Lines of Communication

I’ve written in the past about the use of land-based air defense systems for pressuring adversary air forces’ wartime ability to fly through a maritime chokepoint. Though these systems would not be able to ‘shut the door’ completely against a capable adversary, they could still help reduce the number of adversary aircraft on the margins that could break through the chokepoint in any given raid. This would be of considerable value to a U.S. campaign to protect the sea lines of communication to its East Asian allies in the event of a war with China, or in some scenarios to protect NATO sea lines of communication within the Eastern Mediterranean in a war with Russia. As John Stillion and Bryan Clark point out in their new CSBA study investigating historical competitions between opposing battle networks, actions that disrupt an adversary’s plans or prevent him from achieving his objectives often generate far greater strategic gains than is possible via a singular focus on attriting the adversary’s forces. The latter is often very important to achieving the former; it just isn’t necessarily the only or the most achievable means to that end.   

It is clear, then, that land-based air defenses can be of considerable indirect value to the screening of friendly shipping. But could they also contribute more directly in that mission? Could they be used to substitute in part for escort combatants? The story’s much more mixed on that front.

The first limiting factor is air search radar coverage. A traditional radar can generally only search within its line of sight. The Earth’s curvature affects this the most; for example, a radar mounted 100 feet above sea level will generally be blind to an aircraft 200 miles away that descends below roughly 17,400 feet. Land terrain along the radar’s line of sight only reduces the searchable volume further; this will constrain where a land-based radar can be placed if seaward coverage is desired. And all this assumes the aircraft’s radar cross section is large enough to allow for detection.

These factors can be overcome somewhat by using a distributed fire control network. In theory, an AEW aircraft that detected an adversary’s aircraft (or cruise missile) could transmit fire control-quality radar data to a friendly land-based air defense system. Should the AEW aircraft and the land-based system use highly directional line-of-sight communications to exchange this data, the adversary would find it extremely difficult to intercept let alone exploit the networking pathway.

Even so, this feeds into the second and far more impactful limiting factor: the interceptor missile range and engagement geometry. Pick any U.S. longer-range surface-to-air missile: its maximum advertised range is generally not too much more than 200 miles or so. But this does not reflect the missile’s actual effective range against a particular target aircraft (or cruise missile) in a given scenario. An engagement geometry involving an interceptor flyout that’s more-or-less tangential to the target’s trajectory would have a much shorter maximum effective range than one in which the intercept is nearly head-on. A geometry in which the interceptor would have to overtake the target would have an even shorter maximum effective range. Even if kinematically possible, engageability opportunity windows might be very short based on the interceptor’s flyout distance at a given geometry. The bottom line is that a land-based surface-to-air missile would not be able to directly screen naval forces or protected shipping in waters outside the missile’s engagement envelopes.   

In theory, then, a land-based air defense system might at best be able to help screen shipping in the terminal approaches to a friendly coast. An adversary probably would not hazard its maritime strike aircraft in these waters if segments of the defender’s sea lines of communication lay outside that coverage. In contrast, the adversary might be very willing to use missile-armed submarines inside these waters. A high-speed anti-ship cruise missile fired by a submarine at a target 60 miles or less away (consistent with an attack from the second convergence zone, if one is available) would be very difficult to intercept unless an air defense system was positioned fairly close to the threat missile’s trajectory. It’s hard to see how a land-based air defense system, even if supported by distributed fire control from an AEW aircraft, could make that kind of intercept.

We can therefore see that direct protection of shipping at sea would depend predominantly upon the screening forces interposed between an adversary’s raiders and their targets. Ideally there would be an outer layer consisting of aircraft and an inner layer consisting of escort combatants. If the waters being traversed by a convoy or other protected shipping were outside the effective range of land-based aircraft, carrier-based aircraft might be usable in their place. If carrier support was unavailable, then area air and anti-ship missile defense would entirely depend upon the availability of Aegis combatants. If there were insufficient Aegis combatants to provide this coverage, then the escorts and their charges would be on their own. 

The views expressed herein are solely those of the author and are presented in his personal capacity. They do not reflect the official positions of Systems Planning and Analysis, and to the author’s knowledge do not reflect the policies or positions of the U.S. Department of Defense, any U.S. armed service, or any other U.S. Government agency.

Divine Eagle: A Chinese Airborne Early Warning and Surface Surveillance UAV?

I came across an interesting post at Popular Science’s Eastern Arsenal blog about a developmental PLA UAV equipped with UHF and X-band radars for detection of very low observable aircraft, naval surface forces, and possibly land-based mobile forces as well. A previous Eastern Arsenal post contains additional information including the UAV’s assumed maximum operating speed and altitude; the latter is suggested to be an impressive 25km (~82,000 feet). That makes for a pretty sizable line-of-sight radar horizon.

The UHF radar is likely the primary Airborne Early Warning system and the X-band radar would likely be used for surface/ground surveillance. Unlike our AEW and E-8 JSTARS aircraft, however, the battle management and command and control functions made possible by the radars would be “outsourced” to a command post somewhere else. The operational geometry of the associated network would do much to dictate whether this scheme could be effective in combat.

In theory, the UAV’s transmission of its radar data to “shooter” platforms could also enable Distributed Fire Control (DFC); the latter could use the former’s targeting-quality data to cue the launch of a weapon and guide it to the point that its onboard homing sensors could take over. This is how the Navy Integrated Fire Control-Counter Air concept works. DFC provides a tremendous advantage for survival in a contested zone where use of one’s onboard radar would tell any nearby adversary units with the necessary electronic warfare capabilities where to aim their own weapons.

I’m skeptical of such a UAV’s utility in performing surveillance or reconnaissance beyond the effective protection of PLA fighters or land-based/shipboard air defenses. In the presence of those platforms, though, it could be quite effective—assuming the radar worked as advertised and its data pathways were based on “interior lines of networking.” This provides further evidence low observability alone is insufficient for “stealth;” supportive electronic and/or physical attacks against a sensor like this would be crucial.

The views expressed herein are solely those of the author and are presented in his personal capacity. They do not reflect the official positions of Systems Planning and Analysis, and to the author’s knowledge do not reflect the policies or positions of the U.S. Department of Defense, any U.S. armed service, or any other U.S. Government agency.

Sea Lanes Protection Between the First and Second Island Chains in a Notional Sino-American War

On Tuesday, I summarized China’s potential wartime anti-ship capabilities between the First and Second Island Chains. It stands to reason that the U.S. and allied ability to avoid or parry any PLA attacks in these waters would depend upon the margin of temporary localized maritime superiority—or sea control, if you will—that could be extended around a transiting convoy, replenishment group, or naval battleforce.[i] This margin would likely be highest in the waters that could be persistently covered by fighters, Airborne Early Warning (AEW) aircraft, and wide-area anti-submarine aircraft operating from the Marianas, Japanese home islands, or the central/southern Philippines.

As this sea control coverage thinned out with range, PLA forces would in theory gain more operational flexibility. This might be offset, however, through the intelligent use of the one or two U.S. Navy aircraft carriers available in theater during a war’s opening weeks. I’ve previously noted how these carriers ought to be used to provide situation-dependent sea control support to Surface Action Groups (SAG) operating further forward, and alluded to their utility in providing situation-dependent tactical support to defenders in embattled First Island Chain territories like the Ryukyus. The positioning required for those tasks could also allow their fighters and AEW aircraft to screen CLF groups, military sealift convoys, and prioritized commercial vessels transiting outside effective land-based air coverage. With two carriers working together, it might even be possible to occasionally use actual or simulated shipping as ‘bait’ for luring Chinese strike aircraft raids into aerial ambushes.

It additionally should be noted that the U.S. and allied ability to delay or prevent the Chinese Ocean Surveillance System (COSS) from locating and correctly classifying transiting ships would severely complicate the PLA’s ability to cue effective anti-ship attacks. Emissions control, operational and tactical deception, and physical as well as electronic attacks against COSS assets would be essential aspects of any U.S. and allied sea lanes protection campaign. Emissions control and tactical deception would also greatly complicate PLA strike aircraft and submarines’ job of locating, correctly classifying, and targeting protected shipping. The use of “decoy groups,” perhaps using a mix of unmanned systems and actual manned low campaign-value platforms that together simulated a convoy or naval battleforce, might induce PLA attackers to waste precious time and weapons inventories engaging false targets. Better yet, it might cause them to move out of positions from which they could detect and intercept actual shipping. Attacking decoys would be particularly harmful to PLAN submarines, as every weapon wasted (and in the case of AIP boats, fuel burned moving into attack position and then "breaking datum") would eat into the amount of time the boat could remain on patrol before needing to head home for replenishment, and the time spent "breaking datum" would be time the boat would not be able to hunt effectively. Effective deception and concealment would likely have detrimental psychological effects on PLAAF and PLAN crews; over time these effects might become debilitating—and highly exploitable by U.S. and allied forces in their own right.

Lastly, U.S. political leadership might opt to selectively strike PLAAF airbases, PLAN submarine bases, and related PLA infrastructure on the Chinese mainland with long-range guided munitions in order to suppress PLA operational tempo. This would be especially likely if the PLA had set the escalation precedent of striking allied territories first at the opening of the war. Such strikes would have to be highly bounded and selective in terms of their targets in order to mitigate escalation risks. U.S. Navy submarines and U.S. Air Force intercontinental-range strike aircraft would probably perform these strikes, with additional strikes launched from Aegis combatants operating as offensive SAGs. Reducing the PLA’s ability to cycle anti-ship attackers into the Western Pacific would be of immeasurable help to the sea lanes protection effort.

With all these combined arms contributions in mind, the principal screening challenge from a surface combatant standpoint would be defending convoys and CLF ships against “leaker” anti-ship missiles fired by PLA strike aircraft and "pop-up” missile or torpedo attacks by PLAN submarines. The density of the PLA threat in a given area arguably would determine an escort’s necessary capabilities. Aegis combatants’ area air defense capabilities would probably be highly desirable for escort missions in the vicinity of the Ryukyus, Taiwan, and Luzon given the proximity to the Chinese mainland. It’s important to remember, though, that the U.S. only has nine Aegis combatants permanently homeported in Japan (with two more coming by 2017), and these warships would probably be charged with escorting the Navy’s Japan-homeported carrier, protecting the Navy’s Japan-homeported amphibious warships, executing offensive SAG missions, and performing ballistic missile defense tasks. The Navy has thirty-eight other Aegis combatants homeported in the Pacific, eleven of which are homeported in Pearl Harbor. However, not all would be surgeable due to the inter-deployment maintenance and training cycle (and this says nothing of the surge-readiness impacts stemming from the 2011 Budget Control Act). We might theorize that of the five West Coast-based carrier battleforces, the first might already be forward deployed in or near the Western Pacific as a crisis peaked, the second and third might be surgeable for arrival forward within 30 days, the fourth might be surgeable within 90 days, and the fifth would have to complete its ships’ (abbreviated) overhauls and pre-deployment workups before surging. Some of these Aegis combatants would not be detachable from their carrier battleforces, and those that were detachable might be needed more for offensive SAG operations.

Not all of the Aegis combatants would necessarily deploy with carriers, though. If we assume that two-thirds of the Pearl Harbor contingent surged as a crisis peaked, we might have seven Aegis combatants available for tasking along the First Island Chain. These warships would be well-placed for protecting shipping to the Ryukyus, Luzon, or eastern Taiwan. Even so, their use for these missions would trade against their use in offensive SAG operations.

The story would be similar with respect to the Japan Maritime Self-Defense Force’s (JMSDF) Aegis contingent. Japan fields six Aegis DDGs and plans to build two more by 2020. Nevertheless, their principal mission of homeland ballistic missile defense would prevent some number of them from performing sea lanes defense operations. The South Korean Navy’s three Aegis DDGs are not counted in this analysis as it is unlikely they would be offered up for operations that did not involve direct defense of their country’s sea lanes.

It should be clear that Aegis combatants’ use for direct protection of shipping would trade against a large number of other high-priority missions. Moreover, Aegis combatants would generally be tethered to the western half of the waters between the two island chain lines. This would hardly preclude their use for sea lanes and CLF protection, for example as a forward screening layer by virtue of their positions, but they probably wouldn’t be able to closely escort shipping all the way from port to port.

Therein lies the logic of a small surface combatant possessing medium-range anti-air and anti-submarine capabilities. Such a combatant would be entirely sufficient for close escort within waters in which air defense is provided by friendly AEW and fighter aircraft supported by aerial refueling aircraft. Closer to the Ryukyus-Taiwan-Luzon line, this kind of combatant would backstop Aegis combatants’ defensive coverage of a convoy.

The proposed LCS-derived frigate will possess the towed active and passive sonar arrays as well as helicopter capabilities needed for effective anti-submarine warfare. CSBA’s Bryan Clark has also outlined how it could receive the requisite anti-air capabilities for shipping escort.[ii] These improvements would not allow the LCS-derived frigate to detect a submarine-launched sea-skimming anti-ship cruise missile raid beyond effective shipboard radar coverage, though. Land or sea-based AEW support via the Navy Integrated Fire Control-Counter Air capability would be crucial to that end.

Bryan has additionally proposed a longer-range shipboard anti-submarine missile than the legacy Vertical Launch Anti-Submarine Rocket; such a weapon could be very effective in disrupting a PLAN submarine’s attack preparations.[iii] It’s worth pointing out that if COSS could not provide a PLAN submarine with a targeting-quality tactical picture to support firing anti-ship cruise missiles from over-the-horizon, the PLAN submarine would have to close within the range of its onboard sensors. If we assume the primary use of sonar for this purpose, that range might be one to two convergence zones from a target (perhaps 30 nautical miles in the first case and 60 nautical miles in the second case). A shipboard “rocket-thrown torpedo” able to quickly reach out to the first convergence zone and ideally also the second would thus be highly useful.

It’s important to note that the JMSDF already fields two light destroyer/heavy frigate classes that would anchor shipping protection in the approaches to the Japanese home islands and Ryukyus.[iv] As I noted earlier, though, there might not be enough of them to fully carry the shipping escort load within the waters Japan was primarily responsible for protecting. This suggests the utility of the LCS-derived frigate gaining medium-range anti-air capabilities.

One final point is that there would be a demand for LCS-derived frigates to participate in offensive SAGs. It would accordingly be desirable to backfit as much of the LCS-derived frigates’ anti-surface and anti-submarine capabilities as possible into legacy LCS hulls in order to free up as many of the frigates as possible for shipping protection tasks. The logic for using backfit LCSs instead of the frigates in forward-operating SAGs is simple: since the frigates are not presently slotted to receive medium-range air defense capabilities, and since Aegis combatants would be principally responsible for SAG air defense anyway, then the inclusion of backfit-improved LCSs instead of air defense-capable frigates in the SAGs would not alter the existing concept of operations.

The bottom line is that protection of shipping, including the CLF, would likely be far more resource-intensive than is often assumed in the strategy debates. Sea lanes protection would be absolutely critical to the U.S. prevailing in the war, and as such merits extensive study and analysis. I will note that I have never participated in campaign analysis of these questions, nor have I ever been “read into” any such analyses that might have been conducted. Detailed quantitative analysis may very well prove that some of my key assumptions and conclusions are incorrect. Even so, my errors almost certainly center on the specifics of the threat and not on its general nature or the needed seriousness of the offsetting response.

The views expressed herein are solely those of the author and are presented in his personal capacity. They do not reflect the official positions of Systems Planning and Analysis, and to the author’s knowledge do not reflect the policies or positions of the U.S. Department of Defense, any U.S. armed service, or any other U.S. Government agency.

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[i] The discussion that follows is heavily influenced by CAPT William J. Toti, USN (Retired). “The Hunt for Full-Spectrum ASW.” Naval Institute Proceedings 140, No. 6, June 2014. Toti’s article is seminal on modern anti-submarine warfare and should be read in its entirety in parallel to this post.

[ii] See Bryan Clark. “Commanding the Seas: A Plan to Reinvigorate U.S. Navy Surface Warfare.” (Washington, D.C., Center for Strategic and Budgetary Assessments, 2014), 27, 50-51.

[iii] Ibid; 27.

[iv] A third similarly-capable JMSDF destroyer class exists but would generally be tied to providing air defense support to Kongo-class DDGs on ballistic missile defense patrols.

The CSBA Monograph on U.S. Navy Surface Forces

Over the holiday I read Bryan Clark’s study on reinvigorating U.S. Navy’s surface forces’ abilities to perform sea control tasks. His commendable work casts a light on surface Navy issues that generally don’t receive much attention from the think tank community—and certainly not at such high levels of detail and fluency.

Bryan’s core argument is that the surface Navy is disproportionately organized and armed for reactive defense, and that this implicitly contradicts the maxim that the side that effectively employs its offensive weaponry first in naval battle is generally victorious. He also observes that the primary weapons the surface Navy uses for defense are often at a sizable cost-per-engagement disadvantage to the offensive weapons they counter. These considerations lead him to suggest the surface Navy should cede defensive depth against an adversary’s inbound weapons in exchange for a combination of increased offensive armaments capacity and increased inner-layer defensive density. By doing so, he argues, the surface Navy would be better able to disrupt or destroy adversary platforms before the latter could attack effectively, and any weapons the adversary did succeed in launching would have to contend with a deep (and cost-per-engagement advantageous) arsenal of multiple overlapping short/medium-range defensive systems. 

Bryan addresses quite a number of topics including fleet doctrine, top-level requirements for weapons, ideal characteristics for the LCS-derived Small Surface Combatant, and potential uses of U.S. Coast Guard and Military Sealift Command (MSC) ships to shoulder more of the overseas maritime security cooperation task load. Since several of his ideas relate closely to subjects I wrote about last fall, I will focus my commentary accordingly.

Sea Control, Campaign Design, and the Carrier-Surface Combatant Relationship

Bryan asserts that the Navy’s surface combatants must possess some capacity for attaining and then holding sea control (e.g., a temporary local margin of naval superiority) on their own in a notional major conflict because large-deck carriers’ air wings might not be available to contribute. I strongly agree, but my reasoning is different.

Bryan suggests the carriers’ unavailability might result from their being engaged in power projection operations elsewhere in theater. It seems unlikely, though, that conditions could be shaped to allow carrier battleforces to operate deep within a contested zone at a tolerable degree of risk relatively early in a conflict against a strong adversary. This would be especially true if the contested zone’s inner sections were adjacent to the adversary’s own borders. Furthermore, it normally takes a minimum of two carriers on scene to conduct sustained land-attack operations in even a lesser contingency, let alone to conduct operations of any kind inside a contested zone. Given that the presently-programmed 30-year carrier force structure means deployments of a single carrier within a given region will be the norm unless a crisis erupts, and given that the time lag for a second carrier to arrive on the periphery of a contested zone from elsewhere could be measured in weeks, there is a considerable chance that insufficient carriers would be on hand to perform early-phase land-attack strike tasks. For these reasons, the largest share of these early-phase tasks deep inside the contested zone would likely be allocated to missile-armed submarines and land-based long-range aircraft. Not only would these platforms be less vulnerable in such areas to the adversary’s attacks than carriers, but they would also be comparatively more available for this tasking.

Unlike the case with early-phase deep power projection, however, a battleforce containing a single carrier could contribute immensely to protecting situationally prioritized segments of the sea and air lines of communication that are necessary for U.S. military access to the combat theater as well as for embattled allies’ economic sustenance. A single-carrier battleforce operating from the contested zone’s periphery could similarly provide support to operations by Surface Action Groups (SAG) or other friendly forces further forward on a periodic basis. These would arguably be the most important—and in some cases, irreplaceable—roles for carriers during the early phases of a major maritime war.

This is where the doctrinal changes and capability enhancements Bryan recommends come into play. The in-theater carrier shortage means that mission-tailored U.S. Navy SAGs must be able to operate at some distance inside a contested zone for multi-day periods with limited to no external air support at a tolerable degree of risk. These operations might be offensive sweeps to draw out and then destroy adversary maritime forces. They might be reconnaissance missions or raids against adversary forward operating bases or expeditionary lodgments. They might be missions to provide friendly forces on the ‘frontline’ with supporting fires or defensive coverage. They might be convoy escort missions supporting the flow of supplies and reinforcements to these forces, or perhaps the flow of economic and basic humanitarian goods to embattled allied populations. They might even be operations to induce the adversary to react in ways that other friendly forces could then exploit.

The extent to which surface forces could perform any of these tasks at a particular distance inside a contested zone for a particular length of time would be determined by the margin of temporary local superiority they could sustain under such circumstances. It should be clear that the deeper an operating area might lie within the contested zone (and the closer that area was to the adversary’s homeland), the harder it would be for any SAG to persist in operating there. Bryan is thus absolutely correct in that the more offensive and defensive capacity that can be packed into existing surface combatants, the longer on the margins they would be able to operate more or less on their own at some distance inside a contested zone before their ordnance depletion reached the point that their margin of local superiority—and thus staying power—was all but gone. These considerations combined with the availability of carriers and other maritime forces to support SAG operations as deemed necessary would shape the sequence in which individual maritime operations were conducted a U.S. campaign. Precursor or parallel operations by other forces accordingly might be required to pave the way for a SAG’s operation.

This would not change dramatically as reinforcement carriers arrived in theater. Some would likely be tasked with extending greater protection over intra-theater maritime lines of communication. Others might be used to take on some share of Joint power projection tasks as submarines’ and long-range air forces’ standoff-range strike missile inventories became depleted. It should be noted, though, that these power projection operations could not be performed unless the carriers and their surface combatant escorts had already obtained the requisite sea control. As a matter of fact, a carrier battleforce’s tactical actions to seize and retain sea control could be just as consequential in a campaign context as the power projection tasks they might support. For instance, if a carrier battleforce could sustain a certain margin of temporary local superiority when clashing with the adversary’s maritime forces, its ability to inflict outsized damage or losses on the latter while absorbing tolerable damage or losses of its own would help erode the adversary’s probable advantages in the overall theater conventional military balance as well as arrest the adversary’s campaign progress. Likewise, the adversary’s allocation of maritime forces to fight a carrier battleforce (and any friendly forces supporting it) might result in fewer adversary forces available for operations elsewhere in theater during some period; this could be exploited by other friendly forces including independently-operating SAGs. The use of carriers in any of these ways should of course be governed by calculated risk, and precursor/parallel operations by other elements of the Joint force would very likely be necessary or desirable to create particularly advantageous margins of temporary local superiority.

The Airborne Early Warning Caveat

The greatest challenge facing SAGs operating without external air support would be their ability to detect and engage adversary platforms (or inbound threat weapons) at the most tactically advantageous distances. As I’ve previously noted, AEW is crucial to gaining and then holding sea control under intense opposition. Shipboard sensor ranges are limited by their height of eye relative to the earth’s curvature; an inbound air threat flying beneath or beyond this coverage will not be detected in the absence of offboard sensor support. It should also be pointed out that carrier-organic AEW is presently central to maximizing the effective range of the shipboard SM-6 interceptor missile via the Navy Integrated Fire Control-Counter Air (NIFC-CA) concept. While it would be possible for Air Force or allied AEW aircraft to support U.S. Navy SAGs, I am aware of no plans to develop capabilities for integrating either in NIFC-CA. Nor are there any plans I’m aware of to install the large aperture AEW radars necessary for long-range/wide-area surveillance on unmanned aircraft.[i] All of this drastically affects a surface combatant’s ability to engage an adversary aircraft before the latter can launch its own missiles.

SAGs can mitigate this somewhat by positioning their combatants so that the group’s fused sensor picture provides expanded coverage as well as engagement depth. Not all of these combatants need to employ their active sensors; it is perfectly valid for some to only search using passive sensors depending upon the tactical situation. Nevertheless, actively radiating SAG units expose themselves to counterdetection and targeting by adversary platforms operating outside the SAG’s sensor coverage. The same would also be true for the use of a SAG’s helicopters to perform AEW against inbound sea-skimming ASCMs, as the helicopters’ necessary proximity to SAG units to perform this task would cue the adversary’s reconnaissance and possibly targeting efforts. The risk that a SAG’s active sensor usage poses may remain entirely tolerable if the SAG possesses a sizable margin of temporary local superiority against the adversary’s forces. As this margin decreases, though, tactical (and operational) risk increases. Below some threshold margin, it very simply may not be possible for a SAG to operate at acceptable risk in some area for some span of time without carrier/land-based large AEW aircraft support. This further highlights the importance of a campaign’s operational sequence, particularly with respect to the role of precursor/parallel operations in helping a SAG gain and hold sea control.

Engagement Depth, Ordnance Inventories, and Targeting Confidence

Bryan correctly notes that shorter-range defensive weapons tend to be more affordable-per-engagement than longer-range defensive weapons, and that the latter tend to take up more shipboard space than the former. He consequently argues that by concentrating defensive firepower in a single inner layer with a roughly 30 miles radius, each surface combatant not only gains more favorable cost-per-salvo ratios relative to the adversary’s inbound weapons but also gains more opportunities to engage the adversary’s ‘archer’ aircraft with SM-6 before they can fire their ‘arrows.’

The implication here is that surface combatants are most likely to detect inbound Anti-Ship Cruise Missiles (ASCM) at the shipboard radar horizon. This is certainly true for sea-skimming ASCMs to a considerable degree, but not all ASCMs are pure sea-skimmers. For example, some spend a good portion of their flyout at high altitudes, and a few older types perform terminal dives on their targets. Shorter-ranged defensive interceptors can certainly be used against these threats, but it might be desirable to retain the option of situationally employing longer-ranged interceptor missiles (though not necessarily SM-6) against them as well. It should also be noted that an interceptor missile’s ability to intercept any particular inbound threat is often a factor of the ‘engagement geometry.’ Assuming sufficiently timely sensor detection and tracking of a given air threat, an interceptor missile’s effective range against that threat will be closer to its ‘advertised’ maximum range when the threat is headed more-or-less directly towards the interceptor’s firing unit than when the threat is crossing at a tangential distance to the firing unit. If SAG units are intended to mutually support each other within an inner zone defense, this means that the practical separation distance between those units will be less than the ‘advertised’ maximum reach of their shorter-range interceptor missiles; Bryan notes as much in his Footnote #51 (Pg 20). Many perfectly valid SAG tactics allow for minimal to no mutual kinetic defensive support. Greater separation between a SAG’s combatants might be desirable at other times, though, in order to expand the volume covered by the SAG’s sensors or to support concealment tactics. If either of these are the case, and if some degree of mutual kinetic defensive support is desired, then use of a somewhat longer-ranged interceptor becomes necessary. Lastly, it should be noted that if ‘archer’ aircraft could fire their ‘arrows’ from outside SM-6 range (which is well within the realm of the possible), SAG defenses would have to cope with a much larger inbound salvo. The preceding considerations lead me to conclude that Bryan’s call to rely predominantly on a dense inner zone defense is correct, but that some number of relatively affordable medium-range interceptors that can reach beyond 30 miles will still need to be carried in combatants’ vertical launchers for the reasons I’ve outlined.

Not all inner zone defenses need to be kinetic, however. Bryan correctly observes that Electronic Warfare (EW) systems can contribute greatly to defensive effectiveness. He also correctly observes that the short distances and timeframes involved during inner zone defense mean that even the most effective of shipboard EW systems will not allow a surface combatant to refrain from firing interceptor missiles against a given inbound threat. There are also physics-based limitations on the jamming techniques a shipboard EW system can employ. The same physics suggests the value of offboard EW systems, especially in circumstances where their placement can result in inbound threats never detecting or otherwise locking on to defended combatants.[ii]  With adequate separation between offboard EW systems and defended combatants, it becomes theoretically possible to cause a threat ASCM to commit itself early enough towards a harmless direction such that shipboard interceptor missiles can actually be withheld. Perhaps more significantly, the intelligent use of offboard EW systems can contribute enormously to an overall deception and concealment plan that prevents a SAG from being detected or correctly classified by the adversary in the first place. Consequently, I would add ship-launched offboard EW systems to Bryan’s list of future ‘ordnance’ that would be useful for expanding the surface Navy’s sea control capabilities.

All the same, nothing prevents the adversary from employing similar EW methods to defeat the surface Navy’s own offensive weapons. An adversary’s effective use of EW in tandem with other forms of deception could entice surface combatants into wasting their limited longer-range missile inventories against decoys. As I wrote last fall, the Navy faced this exact problem during the Cold War. Thus, from a purely technological perspective (i.e., excluding the non-material solutions I mentioned in a follow-on piece), the use of multi-phenomenology sensors (and often visual-range examination of contacts) is necessary to have high confidence in a long-range targeting picture. While SAG-organic scouts such as manned helicopters or unmanned aircraft can perform this role against distant surface contacts, it is less clear what organic tools a SAG could to perform it against distant air contacts. Shipboard radars could use non-cooperative target recognition techniques to perform some air contact classification, but their doing so could be subject to EW countermeasures by the adversary. Bryan’s call for improved inner layer defensive density resultantly gains additional importance, as it would provide a SAG’s only other recourse in the event an adversary’s deceptions defeat a SAG’s offensive use of ASCMs or SM-6.

In turn, this reemphasizes my earlier point that the location and length of a SAG operation within a contested zone must be predicated on its ability to sustain its margin of local temporary superiority above some threshold. If it cannot do so on its own, and if the operation in question cannot be delayed until circumstances are more favorable, then it will either need external air support at some stage (such as for detection and outer-layer visual-range identification of air contacts) or the theater commander will have to accept the elevated risks.

Other Thoughts

• One of Bryan’s most important observations was in his Footnote #39 (pg 14). In describing an adversary’s reliance on wide-area surveillance and data relay systems to cue attacks by Anti-Ship Ballistic Missiles (ASBM), he suggests that “surface combatants would be more effective in targeting these enablers, rather than planning to attack mobile ASBM launchers themselves from 800 - 1,000 nm away.” This is absolutely correct. What’s more, these surveillance/reconnaissance 'systems of systems' are likely to be used to cue anti-ship attacks by other platforms such as submarines and land-based aircraft. Degrading or neutralizing these constituent sensor and communication systems—however locally or temporarily—using deception, concealment, or (as feasible) physical attack will be a critical prerequisite for sea control within a contested zone. Doing so essentially represents a 'mission-kill' against the adversary's ability to perform over-the-horizon targeting. At the campaign-level, these anti-scouting efforts will be central to rolling back the adversary’s offensive progress and eroding his military potential in theater. Surface forces will have major roles to play in this fight, but it will often require contributions from other Joint combined arms to be successful. 
• I agree with Bryan’s three desired design attributes for future shipboard missile development: offensive capability, multi-mission usability, and smaller physical size. I would also add wartime producibility to Bryan’s list. 
• I strongly support the Long-Range Anti-Ship Missile (LRASM) concept for all the reasons Bryan articulates. Nevertheless, I believe more analytical attention needs to be paid to how it will be provided with high-confidence targeting cues at distances beyond the range of SAG-embarked aircraft or in hotly opposed areas where the MQ-4C Triton or P-8 Orion might not be risked. The Navy’s Outlaw Shark over-the-horizon targeting experiments of the late 1970s highlighted the extreme difficulties this situation presents, especially if missile cueing depends upon the adversary’s Emissions Control indiscipline.[iii] Visual-range confirmation of a target’s classification may be necessary for employing LRASM with high confidence. This may be a potential major role for the proposed Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) system. 
• Aircraft embarked in combatants will remain the most lethal means for time-sensitive attacks against a nearby adversary submarine in the absence of land-based anti-submarine aircraft support, but as Bryan observes there is a need to buy some time for the embarked aircraft to fly out to the threat. The existing Vertically-Launched Anti-Submarine Rocket (VLA) does not have sufficient range to disrupt attacks by adversary submarines that are solely using their organic sensors to target the protagonist’s battleforce. I therefore strongly agree with Bryan’s recommendation for a new, longer-ranged quick-reaction anti-submarine weapon.
• Bryan is entirely correct that the Navy’s programmed shortfall of Small Surface Combatants (SSC) capable of performing wartime convoy and combat logistics ship escort duties means these tasks would fall on the AEGIS cruiser and destroyer force, which itself would be heavily in demand during a conflict. He is also correct that the SSC shortfall in general is pulling cruisers and destroyers into performing peacetime security cooperation tasks that detract from their combat readiness. I agree with his recommendation that the sea services should find ways to use U.S. Coast Guard and MSC ships to take on some share of peacetime as well as wartime SSC missions. In particular, I think it would be worth examining whether the Coast Guard’s High Endurance Cutters could be outfitted and their crews regularly trained to take on some share of wartime escort duties in low to moderate threat environments (e.g. outside or on the periphery of a contested zone). With respect to MSC ships, though, I would note that their hypothetical combat activities may be constrained by international legal considerations. These need to be fully investigated when developing concepts for how they might be used to take on SSC-type tasks.
• The Navy’s proposed SSC solution is to modify the two existing LCS variants’ designs so that the FY19 and follow ships receive permanently-installed anti-submarine and long-range anti-ship capabilities as well as improved EW capabilities. Bryan reasonably recommended that they should also receive a medium-range air defense interceptor such as the Evolved Sea Sparrow Missile (ESSM) that would allow them to protect escorted units, but this is not part of the proposed program of record. As a result, wartime convoys approaching a combat zone in which there is a considerable air (or submarine-launched ASCM) threat will likely need to be augmented by AEGIS combatants or external tactical air support. This will absolutely be the case if a convoy must traverse part of a contested zone. Convoy demands are likely to be high in a war against a great power adversary, and as such the availability of AEGIS combatants for offensive SAG operations may be limited by the demands on them for convoy protection.

Tomorrow, I will examine the surface Navy’s leadership’s article on SAG concepts in the January Proceedings.

--Updated 8:43PM 1/14/15 to clarify why longer-ranged interceptors might be needed by a SAG if the separation between its units is increased, and to delete a typo in the beginning of the 'Other Thoughts' subsection--

The views expressed herein are solely those of the author and are presented in his personal capacity. They do not reflect the official positions of Systems Planning and Analysis, and to the author’s knowledge do not reflect the policies or positions of the U.S. Department of Defense, any U.S. armed service, or any other U.S. Government agency.

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[i] The X-band AN/ZPY-3 radar on the MQ-4C Triton is a surface surveillance and ship classification sensor. It is not suited for long-range AEW.

[ii] See 1. Dave Adamy. “EW Against Modern Radars-Part 2: Radar Jamming Techniques.” Journal of

Electronic Defense 33, No. 1 (January 2010): 44-46; 2. Thomas W. Kimbrell. “Electronic Warfare in Ship Defense.” Technical Digest, Naval Surface Warfare Center Dahlgren Division, (September 2004): 85-86; 3. Craig Payne. Principles of Naval Weapon Systems. (Annapolis, MD: U.S. Naval Institute Press, 2006), 91-92.

[iii] See Norman Friedman. Network-Centric Warfare: How Navies Learned to Fight Smarter Through Three World Wars. (Annapolis, MD: Naval Institute Press, 2009), 206-210.