March 20, 2019

US nuclear weapons in, around South Korea - including SSBNs

Following Submarine Matters' US-North Korea Missile Issues Much Broader Than Korean Peninsula, March 12, 2019, Josh on March 12 2019 made interesting comments regarding the recent history of US nuclear weapons in and around South Korea. I have bolded, added, extra links and comments in square [...] brackets. Josh wrote:

“US nuclear weapons were previously based in South Korea for decades until their removal at the end of the cold war in 1991. Around the same time, USN vessels also offloaded all tactical nuclear weapons (this would have included the B61 [nuclear bombs on US aircraft carriers]. BGM-109 [cruise missiles with nuclear warheads on US] SSNs, and probably a collection of [nuclear] depth bombs,  ASROC, and  SUBROC warheads.

[See Document A A history of US nuclear weapons in South Korea” (2017) at]  https://www.tandfonline.com/doi/full/10.1080/00963402.2017.1388656

It's worth noting the weapons in Korea were probably directed at Russian Pacific Fleet bases more than North Korea; Japan would not allow warhead basing on their soil (though it didn't question whether docked ships had such weapons, unlike New Zealand).

In the current context, the only relevant US weapons that could reach North Korea are strategic weapons or tactical weapons that are based on US soil. So there is no reasonable posture for the US to adopt that would further denuclearize the Korean peninsula. There are of course tens of thousands of US troops in the ROK that could be traded as a bargaining chip, as well as the economic sanctions which are far more important to the [North Korea]. However the US position is that [North] Korea must make the compromises first - which is understandable given how many previous agreements it has breached or worked around.

Realistically the only thing that will change the status quo is Kim dying of natural causes or some kind of conflict.
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Document A is very interesting on US submarine issues as they relate to the Korea’s.

Document A is by Hans M. Kristensen & Robert S. Norris A history of US nuclear weapons in South Korea” (2017) Bulletin of the Atomic Scientists, Vol. 73, 2017, Issue 6, Pages 349-357, Published online: 26 Oct 2017. The whole Document is published at https://www.tandfonline.com/doi/full/10.1080/00963402.2017.1388656

Snippets on submarines in 18 page Document A include:

“Since [1991] the United States has protected South Korea (and Japan) under a nuclear umbrella made up of several types of weapons: dual-capable fighter-bombers and strategic nuclear forces in the form of bombers and submarines.1

“...In addition to tactical nuclear forces, US strategic nuclear weapons also played (and continue to play) an important role in defending South Korea. This role has taken several forms over the years. In the late 1970s and early 1980s, for example, the US Navy suddenly began conducting port visits to South Korea with nuclear-powered ballistic missile submarines (SSBNs)...

“...The reason for [US nuclear armed submarine] port visits is still unclear, but the timing coincided with the period when the United States significantly reduced deployment of nonstrategic nuclear weapons in Korea. This period overlapped with the years when the United States discovered and attempted to stop South Korea’s secret program to develop nuclear weapons.4...”

“...The SSBN visits ended when the remaining Polaris submarines were retired in 1981, and even though the US Navy gradually built up its fleet of new Ohio-class submarines in the Pacific, American SSBNs have not visited South Korea since January 1981. 

Yet Ohio SSBNs continue to play an important role in targeting North Korea. With their much longer-range missiles, Ohio SSBNs can patrol much further from their targets than earlier submarines. A 1999 inspection of the Trident submarine command and control system identified the SSBNs as “mission critical systems” of “particular importance” to US forces in South Korea (Defense Department 1999Inspector General, Year 2000 Compliance of the Trident Submarine Command and Control System. Report Number 99-167, May 24, 1999, p. 1.http://www.dodig.mil/audit/reports/fy99/99-167.pdf. [Google Scholar], 1). Except for a lone SSBN visit to Guam in 1988, though, Ohio-class submarines did not conduct port visits to the Western Pacific for 35 years.

That changed on October 31, 2016, when the USS Pennsylvania (SSBN-735) arrived in Guam for a highly publicized visit to promote US security commitments to South Korea and Japan. Military delegations from both countries were brought to Guam and given a tour and briefings onboard the submarine, which was carrying an estimated 90 nuclear warheads. “This specific visit to Guam reflects the United States’ commitment to its allies in the Indo-Asia-Pacific,” the US Strategic Command publicly announced, apparently a signal that the US nuclear umbrella also extends over the Indian Ocean (US Strategic Command 2016 Public Affairs, “USS Pennsylvania Arrives in Guam for Port Visit.” October 13.
https://www.stratcom.mil/news/2016/651/USS_Pennsylvania_Arrives_in_Guam_for_Port_Visit/. [Google Scholar]).

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See the whole interesting Document A by Hans M. Kristensen & Robert S. Norris A history of US nuclear weapons in South Korea” (2017) Bulletin of the Atomic Scientists, Vol. 73, 2017, Issue 6, Pages 349-357, Published online: 26 Oct 2017 at https://www.tandfonline.com/doi/full/10.1080/00963402.2017.1388656

Pete

4 comments:

Josh said...

@Pete:

One other relevant note in the context of SSBNs and Korea is the US adoption of the 'W76-2' (W76 Mod2?) warhead for Trident missiles. This program removes lithium deuteride fuel from existing W76 warheads that normally have a ~100kT yield. The resulting single stage (nuclear only, not thermonuclear) weapon is 5+ kT yield for quick response tactical uses. This was recommended by the last US nuclear posture review and largely has to do with Russia's superior tactical nuclear arsenal, it's break from the INF, and it's more disturbing doctrine of 'nuclear de-escalation'. But it would be relevant in the Korean context as the weapon with by far the quickest response time for first use (on the order of twenty minutes from order to delivery). Work has begun and patrols with the warheads is set for some time in 2020 I believe. Presumably they will be carried 2-3 at a time on designated Tridents for tactical only missions against single targets.

Cheers,
Josh

Pete said...

Thanks Josh

The details that you bring up of the actual US and other nuclear weapons environment is so much more helpful than the Mainstream Media merely reporting:

Trump meets Kim in XXXX.

And the MSM then shifts to the nuclear weapons that only Kim needs to "denuclearize".

With the MSM and many shallow "experts" actually expecting there is a prospect that Kim would reverse 3-4 decades of NK hard work on a nuclear deterrent by denuclearizing.

Regards

Pete

Josh said...

@ Pete:

I still use open source like the next guy, I just pull more teeth. If you google around you should be able to read up on W-76-2, though the deployment scheme is my personal supposition: I assume the 'tactical' yield warheads are all on separate missile(s) and I assume because no one only hits a target with *one* nuke, that the warheads are at least doubled, maybe tripled. One target, one missile, 2-3 warheads. If the first warhead goes bang successfully, it fratricides the the follow on warheads, but no one will really care at that point. That is my personal guess at the deployment scheme; take it with a grain of salt.

The British are rumored to have some of their missiles set up with single or double warheads since their only nuclear weapon is SLBMs. In fact I wonder if this 'W76-2' arrangement isn't what they already employ, since the program seems ready for deployment so quickly - I'd have thought defueling the fusion stage would change the center of gravity enough to warrant a flight test of the RV. But maybe that already happened under British auspices. The Trident fleet is all the same pool shared between the two navies; a missile that is on a USN boat might have served on a RN boat before. Same pool of boosters, though I think the RV bus differs in warhead loading and penaides depending on which navy is going to patrol with it.

Cheers,
Josh

Pete said...

Hi Josh

Thanks for those details on how to drop Trident warheads yield down to just a few kilotons or even less than a kiloton.

Relevant to all this might be SubMatt article https://gentleseas.blogspot.com/2014/03/indian-tritium-exports-to-us.html which drew interest from one or two appropriate production establishments.

Regards

Pete