Japanese VLS Submarines?: Nuclear Warhead Tendency

PETE COMMENT

Looking at Wispywood2344's article below, my own research and here. Japan has begun a research program of SSK submarine firing land attack missiles (categorised as "cruise" "ballistic" "hypersonic" "standoff" or a combination in one or two missiles). Japan's research extends to launch by torpedo tube (in the Israeli Dolphin SSK or UK Astute SSN fashion) or possibly vertically launched systems (VLS).

If 533mm torpedo tube fired Japan's existing Soryu and Taigei class SSKs, which already fire torpedoes, ASMs and mines, could be retrofitted (say within the next 5 years = 2028) to fire land attack missiles.  

If the Japanese Government decides on VLS this may be:

A.  by new post Taigei-class SSKs, less likely to carry nuclear warheads. Japan's practice of usually building 10 SSKs per class, tends to indicate a new class, which may have VLS, would be laid down in 2029 with commissioning in 2034.

or 

B.  for a dedicated hypersonic/ballistic missile carrying SSK known as a conventional submarine with ballistic missiles (SSB) more likely carrying a nuclear warhead option from the late 2030s. My reasoning being "Why would South Korea (SK) and Japan go to the expense of building a class of SSBs if their principal weapon, hypersonic/ballistic missiles, are merely conventionally armed" and "For a nuclear armed target country (eg. NK) SK and Japanese missiles would be considered "nuclear/conventional warhead ambiguous" and in any case would prompt "NK to use its nuclear weapons or risk losing them - leading to an NK nuclear response". 

Either A. or B. could be useful for pre-emptive or second strikes against military or command targets in China, Russia (and islands owned by either) or more likely against North Korea (NK).

Japan's VLS study has an element of design-capability competition with South Korea's KSS-III SSBs, including the tendency of SSBs to be nuclear armed. Noting  it is highly unlikely that South Korea would ever by Japan's target. 

As conjectured above a Japanese SSB would tend towards eventually carrying nuclear warheads. Or Japanese SSBs would be further encouragement for the US to maintain its existing (though increasingly unlikely) nuclear umbrella protecting Japan.

See varying US attitudes, over time, to the possibility of South Korean and also Japanese nuclear weapon programs right up to 2016 https://nsarchive.gwu.edu/briefing-book/henry-kissinger-nuclear-vault/2017-03-22/stopping-korea-going-nuclear-part-i

ARTICLE

Wispywood2344, on Jan 8 2023 commented:

The Japanese government has decided to make a major military build-up and has declared that the defense budget for FY2023 will be 27% higher than in FY2022. [1]

It also announced a policy of developing weapons such as [medium-long ranged] standoff missiles.

Here, I would like to introduce matters related to submarines. 

(A) Development of [Japanese] VLS-equipped submarines [4] 

(B) Submarine-launched missiles

Two types of cruise missiles will be developed.

One will be launched from a torpedo tube and probably fly at subsonic speeds. [5][9]

The other will probably be launched from a VLS and fly at hypersonic speeds. [2]

The latter has a land-launched version, reportedly has a range of 2000-3000 km. [8][10]

 (C) Procurement of new torpedoes

The quieter version of the Type 18 torpedo. [3]

The development project to apply a new turbine engine has been underway since FY2018 and will be completed as planned. [8] 

(D) Research on UUV control technology

Establish target detection, class identification, motion analysis technology using passive sonar onboard UUVs, automatic obstacle avoidance technology, and position control technology using inter-UUV underwater communication. [7]

For new information on standoff missiles such as HGM, please refer to the list I prepared if you are interested. [11]

[1] FY Reiwa05(2023) Defense Programs and Budget of Japan

https://www.mod.go.jp/j/yosan/yosan_gaiyo/2023/yosan_20221223.pdf#page=5

[2] ibid.

https://www.mod.go.jp/j/yosan/yosan_gaiyo/2023/yosan_20221223.pdf#page=12

*Look at a submarine firing "極超音速誘導弾" (Hypersonic Cruise Missile).

[3] ibid. 

https://www.mod.go.jp/j/yosan/yosan_gaiyo/2023/yosan_20221223.pdf#page=31

[4] Defense Force Development Plan : Composition of the JSDF

https://www.mod.go.jp/j/approach/agenda/guideline/plan/plan_03.html

[5] FY Reiwa04(2022) preliminary project evaluation : Submarine launched missile

https://www.mod.go.jp/j/approach/hyouka/seisaku/2022/pdf/jizen_11_honbun.pdf

[6] FY Reiwa04(2022) preliminary project evaluation : Research on hypersonic cruise missile

https://www.mod.go.jp/j/approach/hyouka/seisaku/2022/pdf/jizen_02_honbun.pdf

[7] FY Reiwa04(2022) preliminary project evaluation : Research on UUV control technology 

https://www.mod.go.jp/j/approach/hyouka/seisaku/2022/pdf/jizen_03_honbun.pdf

[8] FY Heisei28 (2017) preliminary project evaluation : New torpedo equipped with silent engine

https://warp.da.ndl.go.jp/info:ndljp/pid/11591426/www.mod.go.jp/j/approach/hyouka/seisaku/29/pdf/jizen_12_honbun.pdf

[9] Summary of Proceedings of the 43rd Expert Committee on Policy Evaluation of the MoD

https://www.mod.go.jp/j/approach/agenda/meeting/seisaku/pdf/gijigaiyou43.pdf#page=4

*An outside expert asked about the missile's launcher, and the official replied "Conventional torpedo tube is considered".

[10] Asahi Shimbun (newspaper) [article translates as it is in html] : Long-range missiles will be deployed in phases "in 5 years" and "in 10 years".

https://www.asahi.com/articles/ASQDW5QBXQDVUTFK00B.html

[11] http://blog.livedoor.jp/wispywood2344/others/Japanese_Stand_Off_Missile_Development.html