South Korean Boomer (Bomber in UK RN slang) Ambitions

By Shawn Chung

This article started off as a long email chain between Peter and me, that was a spin off of Peter’s article on a potential South Korean submarine-based nuclear deterrent.

As Pete’s article highlights, the increasing nuclear sabre-rattling by Kim Jong Un and North Korea has not been ignored by South Korea, and while South Korea has secured a nuclear defense deal with the US, developing an indigenous South Korean nuclear deterrent is no longer a taboo subject. 

But what are potential SK nuclear delivery systems? 

South Korea actually has a series of ballistic and cruise missiles under the Hyunmoo program, which is detailed in this excellent article from Navalnews.com. Hyunmoo systems were recently seen at the South Korean Armed Forces Day parade, which included drones, cruise missiles, the L-SAM BMD missile system and the Hyunmoo V, a new 3,000km MRBM. South Korea is also researching Hypersonic Cruise Missiles. 

https://youtu.be/CkLf2rAeKnQ?si=_bdQcN_bYQdyNRBg

Now, while South Korea could potentially equip the Hyunmoo V with a nuclear warhead, it is a land based system and in the information age of spysats and synthetic aperture radar, vulnerable to a pre-emptive strike. Submarine launched nuclear weapons, however, have the advantage of ‘hiding out of sight’ for second-strike and strategic nuclear deterrence, and South Korea already has ballistic missile submarines, so to speak.

Both HHI and Hanwha Ocean are currently building the Dosan Ahn Chanho-class (KSS-III) submarines for the ROKN for nine submarines in three batches.

Three KSS-III Batch-I boats have been completed (one was built by HHI, two by Hanwha/DSME). Batch-I boats are equipped with 6 K-VLS for SLBMs and cruise missiles, and can carry the 500km Hyunmoo 4-4, which has a conventional payload. Batch-I submarines are crewed by 50 submariners, and are reported to displace 3,400 tons (surfaced), are 83.5m in length and use AIP fuel cells, with a maximum range of 19,000KM.

Hanwha started construction of the first KSS-III Batch-II boat, with the keel laid in March 2023. While the three batch-III boats are larger, and while crew size is unchanged, displacement is now 3,600 ton (surface) displacement, 89m in length, they will have updated sensor and combat systems, including lithium ion batteries and 10 VLS.

While the current K-VLS launcher, with a 9.8m length, just fits within the hull of the KSS-III submarines, and they carry the Hyunmoo 4-4, which has a 500km range, so it’s just able to reach Pyongyang if it’s fired off the East coast of SK, near Pohang. This means that the KSS-III have relatively short ballistic missile range, and need to stay within an area around the Korean Peninsula to strike North Korean targets. The KSS-III likely can use Hyunmoo-3C cruise missiles with a 1,500km range, but as the Ukraine-Russian conflict has shown, cruise missiles can be countered by a significantly alert and equipped air defense system.

While first two batches of KSS-III can be considered ‘tactical ballistic missile submarines’, the following three Batch-III boats, the first of which is expected to be delivered as early as 2027, could be a real boomer - an SSB armed with 3,000km (Nuclear) SLBMs.

Batch III boats have always been expected to be the largest of the three batches, and they could incorporate, from the construction yard, large VLSs that can launch 3,000km SLBMs derived from the Hyunmoo V. An South Korean SSB could hide in the Philippine Sea, where its AIP/Lithium Ion would enable the sub to lurk for extended periods of time submerged.

The South Korean Agency for Defense Development, has just issued an RFP for the development of a large VLS that could launch a ‘proper size’ SLBM, with a prototype to be tested underwater by 2026.  Navalnews has also implied that South Korea may adopt a missile module, similar to the Virginia Payload Module to add more firepower to the earlier KSS-III batches.