Mischaracterizing a Notional Deployment of THAAD in South Korea

Last Friday, Sukjoon Yoon, a senior fellow at the Korea Institute for Maritime Strategy, published an opinion piece in The Diplomat regarding the potential implications of a hypothetical U.S. deployment of Terminal High Altitude Area Defense (THAAD) systems to South Korea upon relations between Seoul and Beijing. I fully appreciate the political sensitivity of the issue to the South Korean government and have no comments on that aspect. The article was quite enlightening with respect to South Korean political and strategic considerations.

I take issue, though, with how some of THAAD’s capabilities were described and what the Commander of U.S. Forces Korea was alleged to have said about its notional deployment. First, there’s this:

Jane’s Defence Weekly reported in April 2013 that the first THAAD was installed in Guam that month; it is intended to provide early intercept capability for North Korean missiles during their boost or ascent phase.

I can’t find the Jane’s article being cited, but I’d be extremely surprised if it claimed that THAAD units placed in Guam would be able to perform boost or ascent phase intercepts against North Korean ballistic missiles. As noted above, the ‘T’ in THAAD stands for Terminal. It is designed to perform last-ditch, inner-layer intercepts against inbound reentry vehicles or non-separating ballistic missiles. Its coverage footprint is the immediate area surrounding a defended target. I can’t begin to imagine how close you’d have to place a THAAD launcher to a threat ballistic missile launcher in order to perform a boost or ascent phase engagement, and that’s assuming such an engagement was even kinematically possible.

Next there’s this:

Military leaders in Beijing will have noted General Curtis Scaparrotti’s infamous remarks during his keynote speech at a defense-related forum held in Seoul on June 3, 2014. Scaparrotti recommended the deployment of THAAD to South Korea as a superior option to KAMD, citing THAAD’s capability to engage all classes of ballistic missiles and in all phases of their trajectories.

It surprised me greatly to see that a U.S. General allegedly publicly denigrated an ally’s developmental system. Since the General’s speech as posted on his command’s site doesn’t even reference THAAD or KAMD, I have to assume the discussion of the topic came during the question period. So I checked the English-language Korea Herald article used as the linked citation in the above selection. Nowhere did that article attribute such a statement to General Scaparrotti. Instead, the General merely asserted that he had recommended to his leadership that THAAD deployment should be considered—while also adding the caveat that any such deployment would be subject to a bilateral agreement between the U.S. and South Korean governments. This is echoed in English-language reporting by the South Korean press here and here, and by American press here and here. If there’s reporting to support the claim made against the General, it’s definitely not prominently published in English.

Then there’s this:

What has particularly disturbed the Chinese military is the prospect of the U.S. linking individual sensors, interceptors, and communications assets dispersed all around the Asia-Pacific region into a comprehensive and integrated BMD system to interdict Chinese ballistic missiles in the boost and ascent phases of their trajectories. This would allow THAAD to penetrate and severely compromise China’s air defense zone.

Again, THAAD is a terminal phase system. It has no utility outside of BMD missions. How could it even conceivably “penetrate and severely compromise China’s air defense zone?” The only way any notional South Korea-deployed THAAD units could even conceivably be employed against Chinese missiles is if China had already launched missiles at targets in South Korea.

There’s one other set of technical points in the article I want to comment on:

Moreover, THAAD’s range will extend beyond the Korean Peninsula. The coverage provided by the existing sea-based Aegis system will be greatly extended by the planned deployment of AN/TPY-2 radars. These track inbound short- and medium-range ballistic missiles (SRBMs and MRBMs) with a high-resolution X-band (8-12.4 GHz) phased-array sensor system providing a 120-degree azimuth field out to 1,000∼3,000km, effectively covering the whole of mainland China.

Since it’s clear that the THAAD interceptor could not reach much beyond the Korean Peninsula, the implication of the above is that the system’s greater value to overall U.S. theater BMD would be the AN/TPY-2’s use as a cueing sensor to support remote engagements by other assets. I don’t disagree with that. But the article should have noted that the U.S. would have no monopoly on radars that monitor some volume above or otherwise the approaches to other sovereign countries in East Asia out to several thousand kilometers downrange. The Chinese Over the Horizon-Backscatter (OTH-B) system for maritime surveillance is a primary example. Or, since we’re dealing in hypotheticals, consider the radar coverage if China procures S-400 from Russia. Now that would have real effects on other countries’ air defense zones.

So while I found the author’s political-strategic analyses of the South Korean THAAD question quite interesting, I just don’t see any basis for several of his military-technological arguments…or his assertions regarding General Scaparrotti’s comments.
 

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.  

A Weapon’s Range is not the Whole Story

Illustration of U.S. and threat anti-ship missile ranges from Bryan Clark's CSBA monograph "Commanding the Seas: A Plan to Reinvigorate U.S. Navy Surface Warfare" (pg 13).

The U.S. Navy is clearly at a deficit relative to its competitors regarding anti-ship missile range. This is thankfully changing regardless of whether we’re talking about LRASM, a Tomahawk-derived system, or other possible solutions.

It should be noted, though, that a weapon’s range on its own is not a sufficient measure of its utility. This is especially important when comparing our arsenal to those possessed by potential adversaries. A weapon cannot be evaluated outside the context of the surveillance and reconnaissance apparatus that supports its employment and the overall size of its inventory.

Here’s an example I set up in the endnotes of my article on maritime deception and concealment regarding effective first strike/salvo range at the opening of a conflict:

Optimal first-strike range is not necessarily the same as the maximum physical reach of the longest-ranged weapon system effective against a given target type (i.e., the combined range of the firing platform and the weapon it carries). Rather, it is defined by trade-offs in surveillance and reconnaissance effectiveness and in the number of weapons employable in a short time as the target’s distance from the firing platform’s starting position increases. This means that a potential adversary with a weapon system that can reach distance D from the homeland’s border but can achieve timely and high-confidence peacetime cueing or targeting only within a radius of 0.75D has an optimal first-strike range of 0.75D. It follows that if, for technical, operational, or logistical reasons, the adversary can fire only a few D-range weapons within a defined short period of time, and if his doctrine therefore calls for using D-range weapons in coordination with far more plentiful weapons of range 0.5D, the optimal first-strike range decreases to 0.5D. This does not reduce the dangers faced by the defender at distance D but does offer more flexibility in using force-level doctrine, posture, plans, and capabilities to manage risks.(Pg. 113-114)

The same logic applies following the first strike/salvo, except that the victim of that attack will enjoy much more relaxed rules of engagement for countering the opponent’s surveillance and reconnaissance efforts. In this case, let’s say that Blue possesses a long-range weapon with maximum physical reach of R. Let’s also say that both sides’ anti-scouting efforts inside a given area have neutralized or destroyed surveillance and reconnaissance sensors, not to mention disrupted or degraded sensor-to-network connectivity. Let’s stipulate that Blue’s fraction of R that is covered by high confidence surveillance and reconnaissance is x, and Red’s equivalent fraction of D is y. All other factors being equal, the basic advantage consequently goes to which multiple is greater: Blue’s xR or Red’s yD. Note that if either side's confident surveillance/reconnaissance coverage exceeds their weapons' maximum physical ranges, then that full range can be realized (x or y = 1.0).

The qualities and quantities of sensors, and the architecture and counter-detectability of the (electromagnetic through the air and space, acoustic under the water) data pathways they use to relay their measurements to ‘consumers’ matter just as much as weapon range. Under intense anti-scouting opposition, they arguably matter even more. Remember Wayne Hughes’s maxim: attack effectively first.

Now throw in the inventory-size and salvo-rate considerations on top of the sensing competition. Assuming inventory survivability against attacks is held equal for both sides, if one belligerent has many times more of its long-range weapon than the other belligerent has of its long-range weapon, the former may gain considerable campaign-level advantages over the latter such as greater operational flexibility or greater tolerance for taking operational risks. If one belligerent can salvo off more of its long-range weapon within a short period of time than the other can, then obvious tactical advantages can accrue there as well.

The bottom line is that the question of striking clout is far more complicated than a comparison of range alone. Surveillance/reconnaissance quality and weapons inventory quantity are just as important. The full picture must always be considered.

--Updated 2/26/15 10:32PM based on comments--

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.  
 

Two Cheers for the Secretary of the Navy

Secretary of the Navy Ray Mabus

Secretary of the Navy Ray Mabus has an opinion piece up at USNI News that previews his upcoming "posture" appearances on the Hill before the relevant Congressional committees.  There is a lot to like in his words, and he has been using them and others like them increasingly, and with vigor.  Those of us who have waited for the Secretary of the Navy to advocate for the benefits of Seapower had a rough first four years of this Administration, which were capped off with a Presidential debate in which the eventual winner of the race casually dismissed fleet size as a relic of the past.  At times during the first term, it seemed as if Mr. Mabus were more concerned with tangential issues than with the increasing reality of a mismatch between the nation's need for a strong Navy and the Navy it was funding.

To his credit, the past two years of Mr. Mabus' time as Secretary reflect an increasingly effective use of the bully pulpit to proselytize for the benefits of American Seapower; the USNI piece reflects this evolution.  He is spot on when he points out the sorry state of Navy shipbuilding that existed when he came into office, and he is to be commended for his recent realization that when it comes to navies, size DOES matter.

The Evolution of Ray Mabus has been encouraging to watch, and with two years left in this Administration and the likelihood of his being promoted into the Cabinet dwindling, Mr. Mabus has the opportunity to move into the first rank of Navy Secretaries for reasons other than longevity.  He has taken important first steps, but there is more to be done.

First, he must own up to the Navy's dramatically underfunded shipbuilding account.  His prediction of a 300 ship fleet at the end of the decade rests on funding levels that the Navy has not historically received and which it has been unwilling to request.  The 30 Year Shipbuilding Plan is not believable, and it is an open secret.

Second, he must own up to the growing reality that even the unaffordable Navy that is planned is insufficient to the global requirements that are placed upon it.  Put another way, we are dramatically under-funding a Navy that is dramatically smaller than is required.  Someone needs to talk about the Navy we need, not the Navy that current budget allocations can provide for.

Third, the Secretary needs to actively work Capitol Hill.  It is unfortunate for him that during his tenure both chambers have flipped, but the reality is that there are a lot of Members on both sides of the aisle in need of personal attention from the Navy's most eloquent spokesman. There is a massive education effort needed to ensure the Congress understands the link between national power and Seapower, and Mr. Mabus' famous communication skills are needed, not just with members of the four relevant committees.  Whatever his current allocation of time and effort devoted to "managing" the Hill is, it should be doubled.

Finally, he must get personally involved in acquisition discipline.  The carrier program, the enhanced FF, and the Flight III DDG programs are all at a stage where an engaged and interested Secretary can hold feet to the fire to ensure stable designs are developed and change orders are minimized, while ensuring that non-Navy influencers on cost (read: DoD) are managed.  UCLASS, SSBN(X), and the next generation surface combatant will all move forward on his watch, and all could benefit from an engaged and energized Secretary.

I am encouraged by the talk.  Now, let's see the walk.

Bryan McGrath

Heritage Foundation Index of U.S. Military Strength

Dakota Wood and his team at the Heritage Foundation has taken on the task of assessing U.S. Military Strength.  A complete download of the project's report is available here.  Of particular interest to me was the discussion begun on page 251, which includes a deft, understandable (to non-navalists), discussion of why Navy force structure planning is different from the other Services by the very nature of what it is we ask the Navy to do in peace AND war.

AEI/Heritage Project for the Common Defense Weekly Read Board (Navy)

"House of Cards: Finding a Winning Political Strategy for the U.S. Navy," by Alex Smith (CIMSEC, 02/16/15)

"Ex-Navy Air Boss: F-35s Essential for Carrier Air Wings," by Mark Faram (Navy Times, 02/16/15)

"The US Navy is Building Precision Laser Weapons," by Zachary Keck (The National Interest, 02/18/15)

"LCS vs. the Danish Strawman," by Steven Wills (CIMSEC, 02/19/15)

"China Conducts JL-2 Sub Missile Test," by Bill Gertz (Washington Times, 02/19/15)

"The U.S. Navy's Cruise Missile Nightmare," by James Holmes (Real Clear Defense, 02/20/15)

"Industry: Potential $20 Billion U.S. Naval Sale to Saudi Arabia Picking Up Steam," by Sam LaGrone (USNI News, 02/20/15)

A Case for Emplacing U.S. Personnel on Allied Ships in the South China Sea

Note from Jon Solomon: The article below was written by my Systems Planning and Analysis colleague, Jonathan Altman, to expand upon an idea he suggested during one of our running discussions on deterrence dynamics. Creating a credible extended deterrence ‘tripwire’ is never a simple task; this is arguably even more so at the low end of the conflict spectrum over maritime sovereignty rights or isolated unpopulated ‘rocks.’ I find Jonathan’s proposal quite interesting on that front, and offer it to you for debate.

In the South China Sea, the Chinese are using a “salami-slicing” approach to incrementally shift the norms and territorial balance to their favor, to the detriment of U.S. allies like the Philippines. Until now, the U.S. response to this challenge has been fairly muted; though calls for more transparency and respect for norms frequently come out of the Obama administration, few if any non-verbal steps have been taken to thwart the Chinese approach. However this need not be the case. The act of emplacing U.S. Government personnel aboard friendly nations’ vessels, perhaps including uniformed members of the armed services, could present a major challenge to current Chinese strategy in the region. I will talk more about why this tactic could be so effective in a later paragraph, but first I’d like to address why the Chinese salami-slicing approach has been so successful, and why other attempts to blunt it have had little effect.

To use the famous framework developed by Herman Kahn, Chinese “salami-slicing” strategy has proved effective because they have created conditions in which they have been able to establish and then sustain escalation dominance. By using fishing boats and other non-military craft to harass our allies, seize property, and increase their claims to land features in the South China Sea, the Chinese have rendered U.S. dominance in conventional arms immaterial. The U.S. cannot plausibly use military force to respond to Chinese uses of non-military power against a treaty ally. Because the US has not been able to respond decisively with tools that match the escalation level of those being employed by the Chinese, U.S. policy responses have been limited to official statements that have had little effect thus far due to the lack of leverage. A demand therefore arises for existing tools that can be easily (and cheaply) employed to symmetrically counter Chinese moves at the lowest rungs of Kahn’s escalation ladder. Though there are more tools beyond emplacing US personnel on friendly vessels, this particular tactic seems like a promising place to start. 

It’s critical to be clear up front; this is not an argument to formally dual-crew an allied ship. The legal framework and rules to enable that approach are simply too complex and ultimately unnecessary to achieve the desired effect. What is being suggested is that the U.S. should consider emplacing small groups of U.S. Coast Guard personnel or even other maritime agency personnel (such as U.S. Fish and Wildlife Service officials) as ‘observers’ or ‘advisers’ aboard allies’ maritime law enforcement vessels, and military personnel aboard allied warships or military patrol aircraft. These personnel should principally be armed with cameras, and their purposes would be twofold. First, raise the stakes on Chinese aggression in the region. It is an entirely different calculation to conduct dangerous maneuvers against a Philippine patrol vessel with U.S. Government personnel on board. The Chinese seem comfortable pushing around smaller neighbors knowing that these nations have little recourse beyond lengthy (and largely ineffective) public and private diplomatic complaints. This calculation becomes much different if Chinese strategists were presented with the risk of threatening American lives (whether by ramming or other action) and thereby upsetting a more powerful nation to achieve the same effects. Think back to the Cold War; American soldiers in West Germany were not reasonably expected to defeat a Soviet incursion, but their presence ensured American casualties—which therefore committed American prestige. The ‘tripwire’ forces along the Central European front therefore committed the U.S. to mobilization and retaliation against any Soviet offensive. The same principle applies with American personnel aboard allied platforms.

The second purpose of emplacing American personnel would be to document Chinese transgressions. Even if the mere presence of American personnel does not deter all Chinese actions, providing a direct and timely conduit to the most expansive media networks in the world would likely cause a rethinking of strategy in Beijing. Since the Chinese have chosen to keep action in the South China Sea low on the escalation ladder, global public perceptions of Chinese behavior and Chinese plausible deniability of illegality remain important. If all of a sudden every Chinese transgression made its way onto CNN complete with a verified video account, it seems reasonable to believe that perceptions of China worldwide would be adversely affected, and that the chorus of world opinion might begin to bring uncomfortable attention on their actions as well as a loss of stature.

The intended effect of emplacing U.S. personnel aboard allied vessels ideally should be twofold. First, help our allies by lowering their risk of operations (such as resupplying isolated garrisons) and assuring them that the U.S. is a stalwart friend. Second, negate Chinese escalation dominance by forcing them to confront Americans in order to achieve their ends. This would force them into a choice between moving to higher level rungs on the escalation ladder and therefore incurring a greater risk of conflict with the U.S., or backing off. Whatever course they chose, their incremental approach would be dealt a setback.

Jonathan Altman is a Program Analyst with Systems Planning and Analysis, Inc. who holds a Master’s Degree in International Security from the Korbel School at the University of Denver. 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 Inc., 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.

AEI/Heritage Project for the Common Defense Weekly Read Board (Navy)

"The Navy's Gigantic Railgun is Almost Ready for Prime Time," by Tyler Rogoway (Foxtrot Alpha, 02/09/15)

"Fat Leonard Scandal Jams Up Dozen of US Navy Flag Moves," by Chris Cavas (Defense News, 02/09/15)

"The Navy Just Sank Its High-Speed Future," by Bill Sweetman (Daily Beast, 02/09/15)

"Tomahawk Strike Missile Punches Hole Through Moving Maritime Target," by Sam LaGrone (USNI News, 02/09/15)

"Securing Operational Access: Evolving the Air-Sea Battle Concept," by the Air-Sea Battle Office Staff (The National Interest, 02/11/15)

"A Balanced US Navy of the Future," by Mark Seip (Defense News, 02/12/15)

"Russian Intel Ship Spying on US Missile Submarines," by Bill Gertz (Washington Free Beacon, 02/13/15)

Type 093/094 updates

Recently, there was an article from Taiwanese magazine talking about newly launched hulls of the improved Type 093 program. Since I don't normally trust sources that I have not vetted, I decided to take a deeper look into my notes from the past year and also look through some satellite imagery.

My most recent update on Chinese nuclear submarines was posted here in Oct 2013. That update was the result of reading a 2013 report by the US-China Economic and Security Review Commission that China began building first of 4 improved 093 SSN in 2012. I've since used the designation 093B on this improved variant. Based on my investigation at the time, it looked like the actual work probably started a few years earlier, but the sub first showed up on satellite images bye 2012. That's probably what they were referring to although I do not really know how they arrived at 4 as the projected number of builds. By the time the report came out, the public available satellite imagery already showed the first of the improved 093 SSNs launched at Huludao shipyard, so I was able to confirm it in my blog entry. Since nuclear submarine imagery is harder to come by than other Chinese naval ships due to their strategic nature, I find these DoD/Naval/US governmental reports to be very helpful as guidance since they have sources that I simply don't have access to.

From 2013 satellite images after the report came out, it appeared that 093B may have a hump and look to slightly wider than early 093s. Since that report came out, a 2014 update to the satellite photos showed the new 093B had left Huludao shipyard for sea trials. There was also a really blurry photo of 093B next to a pier that again showed it may have the hump. That Taiwanese magazine (and numerous people on internet forums) speculated that 093B will have a VLS installation, but I think that is very unlikely even if 093B design has a hump due to space limitations. If 093B is actually wider than 093, I would imagine they want to use that space for noise reduction technology. If 094 is up to 30 m longer than 093 with its 12 SLBM launchers, why would adding a 16 cell VLS to 093 not require a visibly longer hull? I think the biggest step from 091 to 093 was creating a submarine that had reliable reactor capable of sustaining top speed of 30 knots. Type 093 is still very loud so the biggest improvement would be reducing the noise level to a more acceptable level. It's possible that Type 095 will carry VLS, but I think it makes more sense to put that on a larger SSGN design.

The past couple of days, I've looked around the usual nuclear submarine locations in China to look for current states of nuclear attack subs. It appears that the Taiwanese photos of 2 side by side 093B submarine to be accurate and they are beside each other at the piers of Huludao shipyard. It's harder to determine with the newer pictures if 093B do indeed have the hump. Moreover, there is another 093B in advanced stage of construction in the dry dock. It is possible the first 093B has returned to the piers after sea trials in various underwater test center or maybe both of the launched ones are new 093Bs. The main support for returning 093B would be the unlikelihood of Huludao launching 2 093Bs so soon after the previous GE photos showing no submarines at the piers of Huludao shipyard. I think the latter case is more likely because sea trials for new attack subs normally take longer and they normally don't seem to return to Huludao after a year. Also, the 2 boats both look more surfaced vs active attack sub, which seems to me means that not all of the stuff inside have been installed yet.

If we go by US-China Economic and Security Review Commission report of 4 093B submarines, then all of the submarines will likely be launched by 2016. It looks like 5 094s have been launched already, so Huludao would be focusing on attack subs at this point. So, what do we know about this improved variant of 093? Based on satellite photos of the most surfaced 091 submarine, the first generation of Chinese attack sub is likely around 93 m in length and 9.5 to 10 m in beam. Of the first two 093s I spotted at Yulin submarine base, they are both around 101 m in length and 8.5 to 9 m in beam. Now, if we use the premise that these 093s are more submerged than the 091s, it's likely the 093s are about the same (or maybe slightly less than) in beam as 091, but up to 10 m longer. It would be hard for me to imagine that 093 would be 1 m less in beam than 091, since that would definitely result in smaller inner hull width. The newer 093Bs look to be around 106 m in length and 10.8 to 11 m in beam. Consider that one of them is in dry docks and the other 2 are more surfaced than the in service attack subs, these are likely to be accurate measurement of the boat's dimensions. So I think this improved variant of 093 submarine is wider and slightly longer than the early 093s. My guess is that with the larger submarine and newer technology becoming available, there is probably going to be real changes inside the submarine with newer reactor, engines and reduction gears in addition to more noise reduction gears. It looks like they are at least comfortable enough with the design to mass produce it since 3 or 4 093Bs are launched or close to launching. Until then, the only attack subs in service will be the 3 091s at JiangGeZhuang and 2 093s at Yulin submarine base.

The next part to look at is China's ballistic missile submarines. There is still the one 092 SSBN at Jianggezhuang submarine base which I think should be converted to SSGN at some point, since it cannot carry JL-2 SLBMs. On top of that, there is the old Type 031 Golf class that appears to still be at Jianggezhuang base even though it has retired already. The lone Type 032 submarine, which was built to replace Golf Class, is now at Xiaopingdao submarine base. It does make sense for Type 032 to be there, since Xiaopingdao is a naval testing center for submarines (and possibly other ships) rather than an active submarine flotilla. That's why no attack submarines are found in that base. It is also close enough within China's Bohai Sea where it would be more dangerous for foreign subs to follow. At the moment, there are 2 094s at Yulin submarine base and 1 094 at at Xiaopingdao. Last year, we had a photo of 3 094s at Yulin submarine base, but photos since have shown 2 there. At the same time, there were 2 094s at the piers of Huludao shipyard based on satellite photos. That would indicate a total of 5 094s have been launched. Based on previous ONI projections of 5 094s, it seems like all of the 094s have alredy been produced. This would corroborate the current satellite photos where the launched and under construction boats are all attack subs. So why do we only see 3 094s on the satellite photos at the moment. My guess is that the 2 094s currently at Yulin are both officially in service. The other 094 that was at Yulin base in 2014 could either be in service or not. If it is in service, then it could be out on a patrol. Otherwise, it is likely to be in Chinese navy's deep water testing center in South China Sea going through deep dive and long endurance testing. It seems like at least 3 094s will be operating out of the Yulin submarine base. The one in Xiaopingdao was probably launched in 2013 at Huludao along with the first 093B. It has likely finished the initial sea trials and is now going through more advanced weapon/sonar/combat system testing at Xiaopingdao. The other 094 that was at Huludao in 2014 is probably going through sea trials right now. There was a gap of about 3 to 4 years (2004 to 2007/8) from the launching of first 094 to the next 2. All 3 of them probably went through testing at Xiaopingdao around 2007 to 2009 range. I think it's likely that all 3 are commissioned by this point. Since there is a gap of about 5 years from the time the 3rd 094 to 4th 094, I think it's quite possible the last two have made some changes vs the earlier ones based on problems found in testing. Satellite photos show that even though the length of submarine are the same, the location of launch tubes may have moved. Overall, the changes in the newer 094s seem to be less than the change in the newer 093s, which would explain the longer time gap between the first 2 093s and the improved 093B submarines. That seems to indicate the flaws in the earlier Type 093s required more time and effort to overcome. It is also possible that greater urgency was placed on Type 094 program due to the need of having a true long range underwater nuclear deterrent.

At current time, the ratio of attack submarines to boomers in Chinese Navy is currently 5 (3 091s + 2 093s) to 4 (1 092 + 3 094s). If we factor in the the submarines that are under construction and in sea trials, it will become 9 (3 091s + 6 093s) to 6 (1 092 + 5 094s). That seems to insufficient number of attack subs protecting boomers. Moreover, the 3 091s are likely to be retired in the coming years, since they have already been in service for 25 to 30 years. The lone 092 seems to be more likely to be converted to a SSGN rather than be decomissioned with the 091s. So it seems like the first Type 095 submarine would needs to launch soon after the conclusion of Type 093B program in order to eventually establish a 2 to 1 ratio between attack subs and boomers. Based on everything I have seen, Huludao does seem to have started work on Type 095 program already.