SSGN (X): Five Large Submarine Payload to Replace Four US Ohio Class SSGNs?

The United States Navy (USN) is required to compensate for the future disarmaments of the four Ship Submersible Guided Nuclear missile (SSGN) Ohio class. The SSGN(X) program or more often called Large Playload Submarine is at the confluence of several needs including that of perpetuating the operational capabilities offered by the four Ohio but also of replacing the USS Jimmy Carter. This program also maintains the prospect of increasing the series of nuclear missile-launching submarines (SSBN or Ship Submersible Ballistic Nuclear (SSBN) of the Columbia class, today set at twelve units and would serve as “ trade off » (barter) in two ways as part of the negotiations on arms limitation to be carried out with Moscow for post-2026.

The signature of the second Strategic Arms Reduction Treaty (START II) on January 3, 1993 obliged the two signatories to significant objectives for reducing their nuclear arsenals. In 1994, reflections ensued within the US Navy regarding the reconversion of part of the Ohio class SSBNs (18) for the benefit of conventional missions. Never entering into force, the START II treaty is replaced by the Strategic Offensive Reductions Treaty (SORT) entered into force on June 1, 2003 which pursues and accentuates the objectives of STRAT II.

The result is a program to overhaul the first four boats of the Ohio class in order to implement the reduction in armaments negotiated within the framework of START II then SORT. The said program began in 2002 and included 718,54 million euros (2008) in expenditure on various works including reloading the nuclear cores and an operational lifespan extended to 42 years. Each project lasted 36 months per boat. The SSBN-726 Ohio entered into overhaul in November 2002 and was returned to the US Navy in January 2006, thus officially becoming the SSGN-726 USS Ohio. The fourth boat left the shipyard in March 2008.

  • SSGN-726 USS Ohio (1981 – 2023?)
  • SSGN-727 USS Michigan (1982 – 2024?)
  • SSGN-728 USS Florida (1983 – 2025?)
  • SSGN-729 USS Georgia (1984 - 2026)
SSGNX five Large Payload Submarine to replace four American Ohio-class SSGNs 1 Defense Analysis | Hypersonic weapons and missiles | Nuclear weapons
Infographic presenting the position of the Dry Deck Shelter or a large underwater thruster (SWUV (Special Warfare Underwater Vehicle) and therefore their wheelbase on the missile deck.

These four boats no longer accommodate in their 24 Missile Launch Tubes (TLM) Sea-Ground Strategic Ballistic Missiles (MSBS or Submarine-Launched Ballistic Missile (SLBM):

The special forces configuration sees 2 TLMs out of 24 serving as airlocks between the interior of the thick hull and two Dry Deck Shelter (DDS) positioned on the missile deck and connected inside the edge via these two tubes. 66 operators of United States Navy Sea, Air, and Land (SEAL) can be accommodated on board, in addition to the crew. Some sources even mention up to 102 operators in this configuration.

However, the stowage of a pair of DDS can only be carried out within a naval base or a port equipped with suitable means, so that their presence can only condemn a minimum of four additional TLMs of the made of their intrinsic length. Only 126 UGM-109 Tomahawk ( Tomahawk - Land Attack Missile (T-LAM) can be siled into the remaining 18 TLMs, at a rate of seven of these missiles per TLM.

The “pure” SSGN configuration is restricted to the embarkation of 66 Navy SEAL operators, without DDS and the associated loads to support them. Of the 24 TLMs, 2 still serve as airlocks and the remaining 22 accommodate UGM-109s Tomahawk : a total capacity of 154 T-LAM.

It is through this last configuration that the four recast Ohios represent a total of 616 tubes. By comparison, the capabilities accumulated in this area since 1984 by the vertical launch systems of the Los Angeles Flight II class SSNs (8) and Improved Los Angeles (23) more lVirginia-class SSNs of Block I (4), Block II (7) and Block III (7) amounts to a total of 588 missiles on 49 boats. The Silent service (American submarine) in 2019 has 54 boats stacking 1204 cruise missiles out of a total of around 6000 tubes for the entire American fleet, or around 4800 supplied by surface ships.

The US Navy maintains the strategic objective of retaining this number of tubes despite the disarmament of the four Ohio (2023 – 2026) and the Los Angeles (2019 – 2030) which will represent, respectively, the loss of 616 and 372 tubes: i.e. 988 downgraded tubes out of the 1204 available in 2019.

The 38 SSNs of the Virginia class from Blocks I to IV will represent, when they are all admitted to active service by the mid-2020s, the sum of 456 tubes. These are the Virginia Block V (10) which will add 400 additional tubes by 2030 for a total of 856, which is still 348 fewer than in 2019. A transitional solution would consist of laying down the Virginia Block VI (5) and Block VII (5) between the end of the 2020s and before 2034 (SSN(X). The total number of tubes would be increased from 856 to 1256, exceeding the 1204 tubes in 2019.

However, what interests the US Navy is not only in maintaining the volume of the salvo but also in holding underwater vessels capable of a volume of fire worthy of a " game changer » on a theater. Several of the recent American operations employed as the first entry into a theater a strong decapitation strike of approximately 90 to 110 UGM-109 Tomahawk : an Ohio class SSGN can assume, alone, in a single salvo, the “ job“. This frees as many SSNs from a necessary concentration contrary to the accomplishment of other missions in the same theater or in others while the relevance for the United States of supporting two major simultaneous commitments is discussed, as always. .

SSBNX class Columbia 2017 Defense Analysis | Hypersonic weapons and missiles | Nuclear weapons
Sketch of the Columbia class SSBN(X) presented in 2017. The detailed studies are only a little over 60% complete in 2019. They do not present any breaks compared to the Ohio but appreciable developments (steering gear in St. Andrew's Cross, for example).

The SSGN(X) program or more often called Large Playload Submarine first appeared in October 2018 in a Congressional Budget Office (CBO) document with a view to replacing the four Ohio-class SSGNs. The US Navy is targeting a unit cost of 6010 million euros (2018) which the CBO considers ambitious given the studies to be carried out to adapt the plans for a Columbia to the military needs identified for this program. The Congressional Budget Office therefore revises this projected cost to 6620 million euros (2018). Preliminary discussions for this possible program target five units derived from the Columbia-class SSBNs. The layups would take place in 2036, 2039, 2042, 2045 and 2048, i.e. three years since the twelfth Columbia was laid down, and would follow the same rhythm.

The Columbia-class SSBNs have 16 missile launch tubes and no longer 24 like their predecessors. This would “force” the US Navy to target five SSGN(X) because the maximum number of tubes would be 560 (16 missile tubes each accommodating 7 T-LAMs), or even only 490 (two missile tubes dedicated to the forces special). This is less than the 616 of the recast Ohios but this volume would be balanced between the slight surplus of tubes (1256 in the 2030s without the SSGN(X) against 1204 in 2019 with the four Ohio class SSGNs). Format which also allows us to envisage a quasi-permanence at sea of ​​an SSGN and in the Mediterranean and in the Indo-Pacific theater.

The choice to develop the new SSGN from the Columbia class is not only a matter of programmatic and industrial rationalities in order to reproduce what worked with the Ohio and to avoid studies of a new class of nuclear submarines. . In the current strategic, diplomatic and conventional framework, the treaty New Strategic Arms Reduction Treaty (New START) which limits American and Russian nuclear arsenals will expire no later than 2026. The number of SSBNs planned as part of the Columbia class was stopped by the STRATegic COMmand (STRATCOM) at twelve boats in order to achieve the objectives of there Nuclear Posture Review 2018.

Washington suggests that an increase in the number of SSBNs (12) is not incompatible with the international commitments of the United States of America from 2026. This being said in the same context marked by the American withdrawal from the treaty Anti-Ballistic Missile (2002) andIntermediate-Range Nuclear Forces Treatyy (INF) in 2019. It is difficult not to see a threat of extending strategic competition to an additional area of ​​armaments. The SSGN(X) program would then serve “ trade off » in potential future negotiations between Moscow and Washington in order to replace the SORT treaty with a new text binding on both parties. China (Types 09-II, 09-IV and 09-VI) and Russia (Boreï class) do not seem to be able, in the current state of things, to keep up the pace.

The US Navy would probably retain its five SSGN(X) or Large Playload Submarine because it is no longer just a matter of adding up the UGM-109 Tomahawk but also to be able to operate future supersonic or even hypersonic vectors designed for A2AD challenges (Aunt-Access/Reserved Denial) and the evolution of naval combat, particularly in terms of anti-ship missiles. The objective shifts from deep strike and strategic strike to potential actions against opposing fleets. Combat on the high seas for anti-shipping once again becomes the priority, particularly in the case of the SSN(X).

The US Navy observes with great attention the development and construction of “mother ship” submarines (or the Ship Submersible Auxiliary Nuclear (SSAN) proposed by HI Sutton) which will number five units within the Russian Navy in the 2030s. The American Navy is historically a pioneer in this type of mission (operation Ivy Bells (1971) but the number of submarines dedicated to this type of mission dropped to only one (SSN-23 USS Jimmy Carter). Russian SSANs are capable of deploying several pocket submarines and remotely operated underwater robots without forgetting installations allowing the use of divers, and probably even divers. Some will even be able to launch them Status-6 Kanyon, “strategic torpedoes” with great endurance equipped with a nuclear charge.

This is why the SSGN(X) better deserves this term of Large Playload Submarine because it is not only a question of accommodating these boats to the use of drones, of which of Extra Large Unmanned Undersea Vehicle (XLUUV). The need mentioned also corresponds to the replacement of the SSN-23 USS Jimmy Carter (2004 – 2034/49?), third Sea-class submarinewolf specially enlarged and adapted for clandestine operations under the sea (visiting wrecks, recovering debris, working on submarine cables, etc.). With the Large Playload Submarine the American Navy aims to sustain the capacity, develop it and increase its volume through the acquisition of five units. Not to mention that it is not excluded that the USS Jimmy Carter be extended from 5 (2039) to 15 years (2049).

f4f408fcf9fec4e71edd119087ce0801 Defense Analysis | Hypersonic weapons and missiles | Nuclear weapons
The USS SSN-23 Jimmy Carter was launched on May 13, 2004. It has a length of 138 meters compared to 108 for the SSN-21 and SSN-22. The submerged displacement is 12 tonnes compared to 139 for the other two units in the class. The additional section is visible at the rear of the massif, distinguished by a slightly different color.

In these new Russian operational capabilities implemented by these five “mother ship” submarines, the US Navy also retains the ability to implement new nuclear vectors: Status-6 Kanyon. This torpedo is designed as a means of circumventing American claims to intercept intercontinental ballistic missiles by claiming to be able to strike port facades with a charge of the order of megatons. The US Navy responds by opening the door, under the Nuclear Posture Review 2018, to the development of low-yield nuclear warheads carried by ballistic or cruise missiles. The American navy has even considered carrying these nuclear warheads on other vectors, such as torpedoes. The SSGN(X) or Large Playload Submarine would then serve a second time as trade off within the framework of American-Russian negotiations regarding the limitation of armaments regarding the particular case of Status-6 Kanyon.

Ultimately, it follows from all these considerations that to meet all these military needs the five boats derived from the Columbias will have to be able to accommodate mission modules formatted around a standard: the missile launch tube. This would keep a series of five submarines as close as possible to the Columbias. And thus avoid building unique buildings like in the Russian navy. This choice would confirm the erection of missile launch tubes to the rank of standard, like the vertical launch silos of surface ships. The versatility of the platforms would be increased tenfold by the development of standardized loads and modules that can be transposed from one submarine to another.

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