KIMS Periscope

KIMS Periscope No. 354

The Joint Strike Ship and the Maritime Contribution to Conventional Strategic Deterrence

freelance specialist
Dr. James Bosbotinis


Plans for the acquisition of an arsenal ship for the Republic of Korea Navy (ROKN) were first announced in 2019, as part of wider naval force development efforts, including what would become the CVX aircraft carrier. The arsenal ship, subsequently designated the Joint Strike Ship (JSS), will contribute to the multi-domain 3K Defence concept, encompassing Korea Air and Missile Defence (KAMD), Kill Chain (also known as the Strategic Target Strike system), and Korea Massive Punishment and Retaliation (KMPR), which is intended to counter the North Korean nuclear and missile threat. That is, the JSS will form part of a wider maritime contribution to the Republic of Korea’s conventional strategic deterrent. Moreover, given the ongoing debate within South Korea over whether the country should acquire its own nuclear weapons, the development and efficacy of advanced conventional weapon systems as a strategic deterrent warrants analysis.

The Arsenal Ship Concept

Originally developed in the 1990s as part of a wider US Navy interest in transformative technologies, the Arsenal Ship was envisaged as a highly automated, minimally-crewed, high-capacity missile-armed vessel, relying on off-board command, control, communications, intelligence, surveillance, and reconnaissance (C4ISR) systems for targeting within a network-enabled battlespace. The concept was essentially for a ‘remote magazine’, equipped with a 512-cell MK 41 vertical launch system (VLS) armed with land-attack (principally Tomahawk cruise missiles, and a naval variant of the Army Tactical Missile System – ATACMS), and surface-to-air missiles (SAM). In essence, the Arsenal Ship would be a one-ship surface action group capable of providing a substantial land attack capability and contributing to the anti-air warfare and ballistic missile defence roles. The Arsenal Ship was ultimately not proceeded with for a number of reasons, including a perceived potential threat to existing force structures. Moreover, Rear Admiral Richard Cobbold, writing in 1997, suggested that the Arsenal Ship concept, whilst ‘newsworthy’, and capable of contributing to the strike, naval gunfire support, and anti-air warfare/missile defence roles, suffered from a lack of flexibility, constituting a fundamental drawback: ‘deploying them forward for reconnaissance, dispersing for low level tasks, contributing to ASW defence, providing tactical information to ground forces ashore, supplementing amphibious decks, and contributing meaningfully to crisis management, are at best problematic’.

Chinese interest in arsenal ships has also been reported, whilst in 2013, the US company Huntington Ingalls Industries revealed what it termed the ‘Ballistic Missile Defense Ship’, derived from the San Antonio-class landing platform dock design. In August 2019, the South Korean Ministry of National Defense announced as part of the 2020-2024 mid-term defence plan that it would procure an arsenal ship capability, subsequently designated the Joint Firepower Ship and latterly, the Joint Strike Ship.

The Joint Strike Ship

In contrast to the US Arsenal Ship concept, the Joint Strike Ship will be based on a surface combatant hull design, the KDDX, incorporate an advanced sensor fit, defensive systems, and function as a warship rather than a ‘remote missile magazine’. In April 2023, it was announced that DSME, now Hanwha Ocean, had been selected to undertake the concept design for the Joint Firepower Ship, with Hanwha Ocean revealing a Joint Strike Ship concept at the MADEX exhibition held in June 2023. Whilst the concept model displayed at MADEX may not reflect the final design configuration of the JSS, it nonetheless provides valuable insights into the intended roles and capabilities the ships will provide. The JSS design includes a substantial armament, including 48 Korean Vertical Launch System (KVLS)-I cells forward, armed with the Korean Surface-to-Air Anti-Missile (K-SAAM) for local area air defence; 32 KVLS-II cells and 15 other vertical-launch tubes amidship; and most notably, two launch systems aft for large missiles such as the Hyunmoo-5. Two close-in weapon systems, fore and aft, are also included for point defence. The JSS will utilise the integrated mast developed for the KDDX.

The 32-cell KVLS-II will enable a variety of offensive and defensive missiles to equip the JSS, including the 1,500 km-range Hyunmoo-3C land-attack cruise missile (LACM), the L-SAM long-range SAM, and potentially, a ship-launched variant of the Hycore hypersonic cruise missile. It is believed that the 15 additional vertical-launch tubes will be armed with the Hyunmoo-4-2 short-range ballistic missile, which can also be launched from the KVLS-II. The Hyunmoo-4-2 can deliver a two-ton penetrator warhead over a range in excess of 800 km. The integration of the Hyunmoo-5 with the JSS will provide a highly potent strike capability: the Hyunmoo-5 is reported to be capable of delivering an eight or nine-ton warhead over a range of 300 km for the prosecution of deeply buried, hardened targets, or a one-ton warhead over a range of 3,000 km. It warrants mention that the launch system on the JSS aft for the Hyunmoo-5 could also be potentially utilised for other roles, namely, to support an operationally responsive space-launch capability.

The JSS is intended primarily to contribute to the 3K Defense strategy, but would also, as will be discussed, have a wider utility in particular as the Republic of Korea seeks to develop its position as a maritime power and ‘global pivotal state’.

The Maritime Contribution to the 3K Strategy and Conventional Strategic Deterrence

The 3K, or Three-Axis, strategy is intended to counter the threat posed by North Korea, through counter-force operations, underpinned by robust ISR capabilities, against key command and control facilities, nuclear and missile forces to pre-empt North Korean attack (the Kill Chain); defeat incoming air and missile threats (KAMD); and employ large-scale precision strategic strikes to respond to North Korean use of missiles and weapons of mass destruction (KMPR). That is, the 3K strategy seeks to provide deterrence both by denial (through counterforce targeting and air and missile defence), and punishment (KMPR). As Ian Bowers and Henrik Stålhane Hiim highlight, ‘This strategy is unique. Few, if any, nonnuclear states have sought to rely on advanced conventional capabilities to deter a nuclear-armed adversary’.

The 3K strategy draws on all three services of the ROK Armed Forces, and within this context, the ROKN provides a valuable contribution. The Incheon and Daegu-class frigates and Sejong Daewang-class destroyer are, for example, armed with the Hyunmoo-3C LACM and contribute to the anti-air warfare, land-attack, and anti-submarine roles, whilst the forthcoming KDX-III Batch II destroyers will be equipped with the KVLS-II VLS capable of launching a variety of missiles, including the Hyunmoo-4-2, and provide an enhanced contribution to the missile defence role. Whilst the new KSS-III Batch I submarines are equipped with a six-cell VLS capable of launching both cruise and ballistic missiles, namely, the Hyunmoo-4-4. Moreover, the emerging requirement to counter North Korean ballistic missile-armed submarines will be a critical role for particularly the ROKN. The inherent mobility of maritime forces, and their reduced relative vulnerability to land bases, also provides added utility, in particular given the potential incentives for North Korea to use tactical nuclear weapons early in a war on the Korean Peninsula, as Robert Kelly explains: ‘Operationally, Pyongyang will face an intense “use-it-or-lose-it” dilemma regarding its weapons of mass destruction as soon as a war starts’. Conversely, as Bowers and Stålhane Hiim argue, the 3K strategy, in particular the Kill Chain aspect, may itself incentivise North Korean nuclear use, contributing to the ‘use-it-or-lose-it’ dilemma. The targeting of the North Korean leadership, also envisaged as part of Kill Chain operations, may further compound the threat of nuclear escalation.  


The JSS will provide a valuable contribution to the 3K strategy, and will also, alongside the ROKN’s surface combatants and submarines, constitute a potent maritime power projection capability. This will be especially so if the CVX aircraft carrier is proceeded with. Whilst there are caveats regarding the implications of targeting the North Korean leadership and counterforce operations, the robust long-range precision strike capabilities being deployed by South Korea, including those of the ROKN, will provide a capability that would not go unnoticed in Pyongyang. The Hyunmoo-4 and 5, especially the latter and its ability to prosecute deeply buried, hardened targets, provide a conventional means of holding at risk facilities that would otherwise likely require nuclear targeting. This is important both in terms of conventional warfighting, and the credibility of a conventional strategic deterrent, but also with regard to the nuclear debate within South Korea.

In this context, the ballistic and cruise missiles that provide a conventional strategic strike capability also provide the foundation for a nuclear deterrent, although pursuing an independent nuclear deterrent would likely result in substantial diplomatic costs. The development of advanced conventional strike capabilities, including the JSS, in addition to their utility vis-à-vis North Korea, also provide a distinct contribution to the US-ROK alliance and Seoul’s ambition to contribute to wider regional and international security. In this regard, the JSS will provide a valuable contribution to the ROK Armed Forces’ wider conventional strategic deterrent, and a potent expression of South Korea’s national intent both as a maritime power and a ‘global pivotal state’.

Bowers, I. (Ed.). (2024). Coalition Navies during the Korean War: Understanding Combined Naval Operations (1st ed.). Routledge.

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