Trump's Past Pro-Japan, SK Nuclear Weapons Position

https://en.wikipedia.org/wiki/Japanese_nuclear_weapons_program#De_facto_nuclear_state advises:

"On 29 March 2016, then-U.S. presidential candidate Donald Trump suggested that Japan should develop its own nuclear weapons, claiming that it was becoming too expensive for the US to continue to protect Japan from countries such as China, North Korea, and Russia that already have their own nuclear weapons.^[50]

[endnote 50 is]

https://web.archive.org/web/20190611080231/https://www.cbsnews.com/news/donald-trump-japan-south-korea-might-need-nuclear-weapons/

"Donald Trump: Japan, South Korea might need nuclear weapons

By Stephanie Condon

March 29, 2016 / CBS News

Republican presidential front-runner Donald Trump on Tuesday night defended his assertion that more countries, such as Japan, South Korea or even Saudi Arabia, may need to develop their own nuclear weapons.

"You have so many countries already -- China, Pakistan, you have so many countries, Russia -- you have so many countries right now that have them," Trump said in a Milwaukee, Wisconsin town hall televised by CNN. "Now, wouldn't you rather, in a certain sense, have Japan have nuclear weapons when North Korea has nuclear weapons?"

Trump said that the United States spends too much money protecting countries like Japan and Saudi Arabia, but "we can't afford to do it anymore."

CNN moderator Anderson Cooper pointed out that it's been U.S. policy for decades to prevent Japan from getting a nuclear weapon. Trump responded, "Maybe it's going to have to be time to change, because so many people -- you have Pakistan has it, you have China has it. You have so many other countries are now having it."

Trump similarly suggested that Japan and South Korea should develop nuclear weaponry in an interview with the New York Times last week.

Following Trump's remarks to the Times, Japanese Chief Cabinet Secretary Yoshihide Suga told reporters that his nation remains steadfastly against owning, making or allowing nuclear weapons. He said this position will "remain an important basic policy of the government."

Trump said he's in favor of potentially seeing countries like Japan develop nuclear weapons because "it's going to happen anyway."

"It's only a question of time," he said. "They're going to start having them or we have to get rid of them entirely.""

On 27 February 2022, former prime minister Shinzo Abe proposed that Japan should consider a nuclear sharing arrangement with the US similar to NATO.^[51] This includes housing American nuclear weapons on Japanese soil for deterrence.^[51] This plan comes in the wake of the 2022 Russian invasion of Ukraine.^[51][52] Many Japanese politicians consider Vladimir Putin's threat to use nuclear weapons against a non-nuclear state to be a game changer.^[52] "

Australia's Trump Era SSN & SSK Choices: Revised

Responding to Scott's at 11/07/2024 12:11 AM comment:

President elect Trump sees himself as a tough, business savvy, negotiator. He does not respect international alliances, even NATO. 

The US Navy is increasingly (and secretly) advising that US industry (eg. principal Virginia SSN builders GDEB and HII) is failing to produce, repair or overhaul sufficient Virginias for USN needs in the 2020s through to the 2040s. Trump may well see AUKUS future Virginia submarines for Australia as a weak Biden Democrat deal [1]. If so Trump might cancel that deal or sharply increase the Virginia sales price to be paid by Australia.

[1] https://en.wikipedia.org/wiki/AUKUS#Australia%E2%80%93UK%E2%80%93US_negotiations

Anticipating the danger of a Trump cancellation of the Virginia offer, the super secretive Australian Submarine Agency likely has a Fall-back Options Planning Section. This section is probably thinking along the following lines:

Even if Trump cancelled the Virginia class offer it is unlikely the US would prevent the UK supplying SSN AUKUSs (which will have US combat system technology integrated by Lockheed Martin) to Australia. There is too much cash for the declining UK economy at stake. Therefore the UK would exert its still considerable political influence on the US to make the SSN AUKUS offer stand. 

On French SSNs and SK SSK/SSBs:

China is certainly unhappy (and India possibly) with any SSNs being supplied to Australia. There are many reasons why France would hesitate to provide  Barracuda/Suffren SSNs to Australia.

-  One being France rates trade and (Indian and Pacific oceans) strategic vulnerability from China higher than trade with Australia.

-  Also until the early 2040s France's limited nuc sub sector is fully committed supplying the remaining Suffrens and the 4 x third generation SSBNs https://en.wikipedia.org/wiki/SNLE_3G to the French Navy. This is to the exclusion of multi-SSN foreign orders. 

-  Australia was also unimpressed with France's nuc subs for the French Navy first priorities expressed by France in 2021. French Navy priorities were to come first before the delayed Australians Attack-class program was fully tackled some time in the 2030s. On those French priorities see my https://gentleseas.blogspot.com/2021/02/frances-new-ssbn-aus-attack-class-2nd.html

I don't think the South Korean (SK) KSS-III, with its heavy K-VLS SLBM loadout , is suitable for Australia's strategic circumstances. The PRC target is too far for slow, medium range, KSS-IIIs (compared to fast, long range, SSNs) to sail from Fleet Base West to within (future Australian nuclear missile) striking distance of PRC coastal targets.

However if SK industry, in SK, in under 10 years, could build standard SSKs, like the DSME-3000 (which is not burdened by K-VLS silos and has AIP and LIBs) then it may be a good and time sensitive replacement for the Collins. See https://en.wikipedia.org/wiki/KSS-III_submarine#DSME-3000 .

The Virginias for Australia were never to be built in Australia, so SSKs, like the DSME-3000, need not be built in Australia. Submarine building in Australia (ie. at Osborne, Adelaide) typically takes 3 times as long at 3 times the price.

Day Before the US Election: AUKUS Virginia Subs?

After 10am Wednesday Australian Eastern (AE) time US swing state Exit Poll https://en.wikipedia.org/wiki/Exit_poll results may start pointing to a winner. After AE 4pm, once Alaska and Hawaii voting has ended, official results may start flowing in in significant numbers. If it is a landslide, by AE 7pm we may know who won.

Iowa (6 votes) is usually Trump territory. According to election “oracle” Ann Selzer https://en.wikipedia.org/wiki/Ann_Selzer Harris may be ahead in Iowa, https://www.abc.net.au/news/2024-11-04/donald-trump-criticises-poll-after-kamala-harris-prediction/104556162 . 

In part due to this new Iowa expectation Trump may be unnerved, feeling he is losing. Hence Trump has returned to his 2020 mantra “this Election has been stolen”. Such talk may be a Trump mistake immediately before this 2024 election as it may remind Americans of the Trump prompted January 6, 2021 Capitol riot.

It is widely assumed the 7 swing state votes will decide the whole Election. https://en.wikipedia.org/wiki/Swing_state The swing states are Pennsylvania 19 votes; Michigan 15, Wisconsin 10, North Carolina 16; Georgia 16; Arizona 11 and Nevada 6 (Nevada has many postal votes that delays the final results). All are considered “tossups” as they are so close. Like Iowa Florida (30 votes) needs close watching. Florida is currently assumed to be a Trump state (he won it by 3.36% in 2020), It was Florida that won George W. Bush the 2000 Election by only 537 recounted  votes. https://en.wikipedia.org/wiki/2000_United_States_presidential_election_recount_in_Florida  

There might be no clear result on November 5 US time (November 6 Australian time). Instead it may be so close there may be a week of vote recounting. This is especially in the 7 Swing States and maybe Iowa and Florida. The Presidential winner might then emerge after Sunday 10 November.

If Harris wins it will likely be continuity after January 20, 2025 Inauguration Day. https://en.wikipedia.org/wiki/2025_United_States_presidential_inauguration

The ugly alternative? The Australian Government and most informed Australians are very nervous about the possibility of a Trump win.

Trump sees himself as a tough, business savvy, negotiator. He does not  respect international alliances, even NATO. The US Navy is also increasingly (and secretly) advising that US industry (GDEB and HII) is failing to produce, repair or overhaul sufficient Virginias for USN needs in the 2020s through to the 2040s. Trump may well see AUKUS future Virginia submarines for Australia as a weak Biden Democrat deal [1]. If so Trump might cancel that deal.

[1] https://en.wikipedia.org/wiki/AUKUS#Australia%E2%80%93UK%E2%80%93US_negotiations

Part 4: Slew of Developments in the Indian Nuclear Submarine Program: New VLF Station and SLBM Updates

To wrap up this Four-part SubMatts series on the Indian nuclear submarine program, I present two separate developments that emerged in mid-late 2024.

The first is the establishment of a new Very Low Frequency (VLF) communication facility of the Indian Navy in the landlocked state of Telangana in south central India. Used for communicating with submarines without requiring them to reach periscope depth, the new facility would be located some 60 km from the state's capital city of Hyderabad (where your's truly currently resides). The foundation stone marking the start of construction was laid on 16 October 2024 by Indian Defence Minister Rajnath Singh.

The new facility, which is over 300 km from the nearest coastline, offers a more survivable location which is at less risk of being attacked, destroyed or degraded compared to the current submarine communications facility which is located at INS Kattabomman. Kattabomman is in the state of Tamil Nadu and only around 20 km from the coast on the southern tip of India.

Satellite image (via Google Maps) of the facility at INS Kattabomman
---

Notably, the facility at INS Kattabomman has both VLF and ELF (Extremely Low Frequency) transmitters. The ELF band is capable of communicating with submarines at much lower depths, and is therefore more advantageous to use for nuclear-powered boats. It's not known at this time whether the new station at Telangana will also incorporate an ELF facility down the line. 

++++

The second thing I'm writing about is the SLBM program. There have been a few 'releases/deliberate leaks' of SLBM visuals let into the social media space by the authorities (as I don't believe anyone could have acquired them of their own volition).

For example, the video below which shows the K-4 SLBM being ejected from its test pontoon underwater. It then gains altitude by means of nose cap-mounted booster plumes (a method used on older Soviet SLBMs like the R-29). Then the nose cap itself is ejected and the missile's first stage solid motor takes over propulsion. A video of the above-water launch sequence existed before (it can be seen in the K-4's Wikipedia article linked above) but it was of a considerably lower quality and did not include the underwater pontoon-ejection part.

There has also been an image of what seems to be a 'salvo launch' - multiple missiles launched over a short duration - of two K-15 SLBMs, presumably from INS Arihant. It is not known when this salvo-launch test took place (possibly during this bout of testing in 2018). But it goes toward proving a significant capability when it comes to delivering effective deterrence. That is being able to launch multiple nuclear warhead-equipped missiles as quickly as possible. This would be necessary if the SSBN in question has to serve its purpose of performing second-strike. That is a retaliatory strike following an adversary's first strike (considering India has a No-First Use (NFU) policy) before the SSBN itself is probably found and destroyed.

Given the distance between the two points of launch, it would appear that this salvo-firing test was conducted from a submarine that was moving
---

A further piece of my analysis regarding the Indian SLBMs would tie-in to this older article on SubMatts. This raised the possibility of DRDO's ballistic missile-related propulsion R&D work having matured to a degree that no longer necessitated a prominent, raised missile compartment or 'hump' on the S5-class SSBN design. As the solid-fuel and rocket motor technologies advance, it becomes possible to deliver the same payload to the same range as before, but with a missile that is smaller and lighter.

On that note, this excellent comparative artwork (shown below) made by Orion Intel depicting India's Agni-5 IRBM (the government refuses to call it an ICBM). It is in its original configuration on the right, compared to the newer configuration on the left, which is based on photometric analysis of the images revealed during the MIRV test earlier this year.

Comparison of the original Agni-5 and its MIRVed version. Via Orion Intel on Twitter (now X)
---

The newer 'MIRVed' configuration - called by many 'Agni-5 Mk.2' has a different nose cone arrangement. It is noticeably shorter (note the upper black inter-stage section) than the original that was first tested over 12 years ago in 2012. This is in spite of the MIRVed configuration having to carry heavier payloads. Significant progress in miniaturization of ballistic missile stages and motors over the last decade might not be a bad conclusion to draw, although there are several other variables to take into account.

In any case a shorter Agni-5 Mk.2 would certainly explain why the newer hydrodynamic models of the S5 SSBN don't feature a prominent missile hump seen on earlier S5 test models. Improvements in R&D would find applications across the entire gamut of strategic ballistic missiles. Note that the S5s will eventually carry the more advanced, longer range K-6 SLBM. 

With that, this SubMatts series covering recent developments in India's nuclear submarine program comes to an end.

Cheers Gessler

Part 3: Slew of Developments in the Indian Nuclear Submarine Program: First Two SSNs Funded

On the 9th of October 2024, The Cabinet Committee on Security (CCS), the apex decision-making body of the Indian Government regarding all Military matters, has officially granted its final seal of approval to the Indian Navy's nuclear attack submarine program, now designated as Project-77 (previously known as Project-75A).

A sum of Rs. 40,000 crores (equivalent to about US$4.8 Billion) has been allocated toward the construction and acquisition of the first two boats out of a planned total of six.

Artistic impression of the Indian Navy's SSN by Nilanjan Das of the India Today magazine (not representative of actual design)
---

Veteran journalist Sandeep Unnithan who has reported on the Indian nuclear submarine program for over a decade has stated that the P77-class SSNs would incorporate a 190MWth reactor which would represent a generational leap over the 83-100MWth PWRs of the Arihant-class. Sandeep Unnithan can be safely assumed as having sources inside the program or at least being a 'designated' individual through which the Government and/or the Navy publicizes developments. Of note is the fact that Mr. Unnithan (then working for India Today magazine) was the first journalist who reported that the 3rd and 4th Arihant-class boats will be larger than the first two, years before the S4 boat first appeared in public. Satellite images from late 2021 vindicated him.

The new 190MWth reactor, known as CLWR-B2 is likely based on or at least built along the same lines as the Russian OK-650B that powers the Akula II-class SSN that India took on lease between 2012-2021. It would also be prudent to estimate that the CLWR-B1 that powers the Arihant-class was derived from the VM-4 reactor family that powered the Charlie-class SSGN that India leased between 1988-1991. However, any help or guidance from Russian agencies (whether in design itself or at least in the design-validation phase) is unlikely to ever be publicized by either side due to obvious reasons, such as eliciting nuclear proliferation concerns.

On both these reactors, it's likely a great deal of redesign and redevelopment was involved in order to bring them up to modern standards of the time - as well as getting them to work optimally in the warm-water conditions of the Indian Ocean as opposed to the freezing waters of Russia's operating environments. They're still likely to use the same level of reactor fuel enrichment as most Russian marine PWRs (~45% enriched HEU). However, I think it can be safe to assume that the new reactor will differ from its baseline Russian design (presumed by me to be OK-650B) to a significantly greater degree than the Arihants' reactors difference from the VM-4.

With around ~60MWe of total electrical power (assuming a 33% efficiency on a 190MWth thermal output), the P77 SSN would be well-placed to incorporate the 35MW Nuclear-Electric Propulsion (NEP) setup. This would involve a silent electric motor replacing the noisy reduction gearing used in older submarines. This is also known as Turbo-Electric Drive, known to have been in the works for the Indian Navy. Assuming this setup is indeed intended for the SSN project, it can be a reason as to why a significantly higher degree of redesign may have been necessary for the CLWR-B2's power delivery system - especially the secondary loop setup - as the OK-650B was not originally meant to work with NEP.

Above is a publicly-available Expression of Interest (EoI) document (sourced via the Twitter handle of strategicfront.org) calling for industry to develop a 35MW Electric Drive solution for future submarines of the Indian Navy.
--- 

For comparison, the French Navy's Barracuda/Suffren-class SSN uses a 20MW NEP setup fed by a 150MWth LEU reactor to drive its pumpjet propulsor. Notably, the setup on Barracuda-class is only designed to use the nuclear-electric solution up to a certain speed (let's say 20-25 knots) for relatively silent transit. Beyond 25 knots the submarine has to rely on its backup conventional propulsion that is understandably more noisy - in order to attain higher speeds (up to a maximum of 30 knots I would assume).

The Expression of Interest (EoI) documentation above also calls for the Indian NEP setup to drive the submarine to a maximum speed of 25 knots. It's likely that the P77 would also have to fall back on a conventional setup to go faster (again, let's say it can do a maximum of 30 knots or more). Either way, even without the NEP, this reactor should put the P77 in a very good place in terms of speed and performance when going up against any given opponent SSN, such as the new Type-093B of the Chinese PLA Navy. Actually, the P77 is very likely to enjoy an advantage in those regards against the Chinese boats - barring any considerable improvement the PLAN manages to make in the decade-plus it would take for the P77 to arrive.

Also worthy of note is the fact that, at least according to the the EoI document above, the nuclear-electric setup being pursued by the Indian Navy clearly calls for the P77's NEP to drive a pumpjet propulsor. Is that enough reason to assume the P77 will have a pumpjet? We'll see.

Example of a turbo-electric generator manufactured by India's state-owned BHEL corporation for commercial applications. BHEL is very likely to be the contractor responsible for building any NEP solution for future submarines.
---

This same reactor and NEP propulsion setup are also likely to drive India's upcoming "S5" class of next-gen SSBNs. The S5s will be much larger, believed to displace between 13,000-14,000 tonnes, with 12 or more vertical launch silos. The S5s will perform a very different mission (deterrence). Hence S5 reactors will have to cater for different SSBN power delivery needs  (smooth and gradual acceleration) compared to the rapid stop-starts of SSN operations.

Based on reports from official DRDO publications (pictured below) it's evident that R&D work on both conformal bow-array sonars as well as planar-arrays (ostensibly used for flank-array setups) is/has been ongoing in India for several years. It's difficult to say which R&D program might or might not find a real-world application on upcoming submarine programs. I think it can be safely said that there's at least a determination in the Indian Navy to advance past the older cylindrical-array sonar setup used in the bow of the current generation of Indian nuclear boats. Among SSNs that are currently being built, the Astute-class comes to mind as one that has a conformal bow array.

Screen-grabs from the DRDO's official 'Technology Focus' publication, detailing some R&D work on next-generation sonar solutions.
--- 

While there's no official word on this, I would estimate using a 190MWth reactor, there would be enough power on tap for the P77 SSN to incorporate additional mission sets beyond pure hunter-killer duties. This could include carrying a pack of vertically-launched Land-Attack Cruise Missiles (LACMs) like the Nirbhay. It remains to be seen what the configuration of the P77 SSN class will be. I would estimate its surfaced displacement to be somewhere between 5,000 and 7,000 tons. P77s will likely be larger than the 5,300 tonne French Barracuda/Suffren-class but possibly smaller than the Royal Navy's 7,400 tonne Astute class and the US Navy's 7,900 tonne Virginia-class (Blocks I-IV).

I personally do not believe in the reports in some sections of media (like this article from the Times of India (TOI)) that says the SSNs will displace 10,000 tons. Such a displacement would make P77s similar to submerged Improved Akulas. I think the TOI reporter in question either misinterpreted the information brief given to him, or the brief itself was a deliberate attempt at misdirection. Either way, I think we'd do well to believe that the P77 would incorporate an entirely new hull design compared to the Arihant - as I believe that the Arihant-class's internal bulkheads would probably be too small to accommodate the 190MW reactor compartment.

All that said, I think we can expect that the first P77 will be commissioned in the mid-late 2030s. This is assuming the construction starts in 2025, with a build time of between 8 and 10 years followed by sea trials. Much would also depend on how much technology being rapidly iterated over the Arihant-class finds application on the P77.

It's worth noting that even going by what's known so far, every single Arihant-class boat appears to be significantly different from the last owing to continuous technology insertion i.e. improved reactor and hull extension. It is also possible the upcoming S4* might turn out having a pumpjet. This is if a decision were taken to de-risk the P77's and S5's next-gen propulsion setup by testing the pumpjet on S4*.

It's also possible that the eventual requirement will be extended beyond the six P77s currently sought, to twelve, as I previously theorized. This is keeping in mind the construction of a new large, higher capacity, dry-dock at SBC (refer the satellite image in Part-2 of this series). It is very likely that at some point within the end of the 2020s, the Indian Navy could have both the new SSNs and S5-class SSBNs under construction at the same time, They might also be delivered simultaneously over a period of time in the 2030s. Unfortunately, being a strategic program (for carrying nuclear weapons) the funding modes for the S5-class boats will be secret. None of the public reporting such as cabinet approvals or funding details applied to the P77s will likely apply to the S5s.

The upcoming part (probably the last) of this SubMatts series will cover a few updates regarding some ancillary programs that support India's nuclear submarine effort without being directly a part of it.

Part 2: Slew of Developments in the Indian Nuclear Submarine Program: Fourth SSBN Launched

Following the launch of the first 'Stretched' Arihant-class boat known as "S4" in December 2021, the second boat of the Stretched variant, tentatively designated as the "S4*" (pronounced S4 Star), was reportedly launched (released from the dry-dock into the water) at the Ship-Building Centre (SBC) in Vizag on 16 October 2024.

Unlike the first two boats (S2 Arihant and S3 Arighaat) in the class, the next two (S4 and S4*) are a Stretched variant with Eight vertical launch tubes as opposed to Four on the first two vessels. Though these tubes are also of the same variety and can accept either 8 x larger SLBMs or up to 24 x smaller, short-ranged ones, in my opinion it is extremely unlikely for the Arihant Stretch boats to carry any K-15s, as it is plausible now that even the Arighaat no longer uses them owing to limited utility due to short range.

As a result of the additional missile compartment, the Stretched boats are believed to be approximately 20 meters longer and displacing about 1,000 tons more than the base version of the class, bringing them up to about ~130 meters long with a (presumably surfaced) displacement of about 7,000 tons - compared to 113 meters and ~6,000 tons of the Arihant.

Image of the earlier S4 SSBN (top) shown next to the smaller Arihant (lower down) in a satellite image published by the International Institute of Strategic Studies (IISS). Using this here because no real photograph exists of the S4* as yet.
---

The K-15 missile's intended purpose as a technology-demonstration platform for submerged launch operations may have been served to it's conclusion. So it would be prudent to expect the Arihant Stretch-class to only carry 8 x K-4 SLBMs. It's also likely that the S4* might eventually receive the in-development K-5 which reportedly will have intercontinental range (above 5,500 km) by the time it enters service.

Both the S4 (widely expected to be named INS Aridhaman) and S4* would also more than likely be equipped with the same improved 'CLWR-B1v2' reactor with ~100MWth (perhaps converting to 35MWe total electrical power (divided between propulsion and hotel load) that also supposedly equips INS Arighaat.

Comparative artwork of standard Arihants (S2 and S3) and the subsequent Stretched version (S4 and S4*). Courtesy H.I. Sutton of Covert Shores
---

The S4, launched in late 2021 as mentioned above, is expected to be commissioned into service at some point in early or mid-2025 following intense Harbour Acceptance Trials (HATs) and Sea Acceptance Trials (SATs) for the last 3 years. Assuming the HATs and SATs for the S4* take place on a similar timescale, we might see India's fourth SSBN commissioned by around 2028.

While rumours persist of the line at SBC being extended to produce a 3rd Stretched Arihant-class (5th of the overall class), there is no official information yet regarding that proposal. So take the rumours with a pinch of salt. As far as reliable sources go, I think we'd do well to believe that the Arihant-class build program will have ended by late 2024. Only fitting-out, trials (perhaps including a K-4 launch test from S4) and commissioning remain on the table before the class can be officially considered done and dusted.

That would also mean that the dry-dock that built these boats is now free to commence the process of tooling-up for building the next class of larger SSBNs (designated S-5 class) for the Indian Navy. That is assuming the new dry dock (picture below) shaping up at the SBC facility is for SSNs while SSBNs would continue to be built at the older dry dock.

The new, larger dock (northern one) and the older, smaller dock that built Arihant and its Stretch versions (southern one, with the "L&T Heavy Engineering" pin on top)
---

Speaking of SSNs - important developments in that program are going to be the subject for Part-3 of this series - so stay tuned!

Part 1: Slew of Developments in the Indian Nuclear Submarine Program: Second SSBN Commissioned

A series of considerable developments took place in India's nuclear submarine program over the last few months as I took a break from online activity owing to computer trouble. I've decided to break my write-up into several parts so that information can be provided in smaller bite-size parcels instead of a single, huge post.

Part-1 is going to be about the second ballistic missile submarine of the Arihant-class, known in the parlance of the Advanced Technology Vessel program as "S3".

The S3 boat was commissioned into service on 29 August 2024 under the name INS Arighaat and the pennant SSBN-81 (first-of-class INS Arihant was SSBN-80). Like the Arihant, the new boat also has the same number of vertical-launch tubes for Submarine-Launched Ballistic Missiles (SLBMs) - Four.

The only available image of the INS Arighaat at sea - a hazy photo taken by a civilian at RK Beach near Vizag, India. Image shared on social media by journalist Sandeep Unnithan

However, unlike the Arihant which carries 12 x K-15 short-range (750km with typical payload of ~1 ton) SLBMs triple-packed in each tube, the Arighaat is believed to only carry 4 x of the medium-range K-4 SLBMs (3,500km with ~1 ton payload), one per tube. Though both submarines retain the ability to carry both types of missiles, both of which are understandably meant for nuclear delivery, as per need.

Also unlike the first boat in class, the Arighaat is believed by some informed opinions to incorporate an 'improved' PWR or Pressurized Water Reactor that delivers an uprated thermal output of ~100MWth compared to the 83MWth of the Arihant's reactor. The increased thermal output can translate into a minor but proportionally higher amount of electrical power on tap that can be used for the submarine's various electronic systems.

While no known iteration exists in the nomenclature to differentiate the improved reactor from the Arihant's baseline CLWR-B1, for sake of avoiding confusion I'd go ahead and designate the new reactor as CLWR-B1v2.

One of the Verticle-Launch Tubes of the Arihant-class, seen here in a triple-pack configuration meant for the K-15 SLBM

The development, testing & certification of the uprated PWR configuration would have been the likely reason for the long gap between the commissioning of S2 (Arihant) in 2016 and S3 (Arighaat) only in 2024. Not to mention, any faults or production engineering-related shortcomings that would only be discovered after several years of at-sea operation of the first boat - which was also the first nuclear-powered submarine that was built in India - would have possibly necessitated a revisit to the drawing board to ensure that the second boat would have those issues addressed before it's certified for active service.

Subsequent boats are likely to be commissioned at a faster pace.

In the next part I'll cover another bit of important news - the launch of 'S4*' which is the 4th and supposedly last of the Arihant-class SSBNs.