KIMS Periscope No. 328
ROK Navy and Maritime Security: Persistent Presence & Expeditionary Capability
Professor U.S. Naval War College
The views expressed here are the author’s alone and do not represent the official position of the Navy, the US Department of Defense or the US government.
I want to thank CDR Kwon Youngill ROKN and LT Cody Roberts USN for their helpful comments on earlier drafts but any errors are mine.
The Korean security environment is changing. In the early years, the Republic of Korea (ROK) and the ROK-US alliance were focused on deterring another land invasion across the demilitarized zone. Over time, the threats have evolved producing a more complex and challenging threat matrix for South Korean security. In addition to conventional forces, concerns now include North Korea’s nuclear weapon and missile programs along with a troublesome cyber capability.
Often underappreciated are the increasing challenges in the maritime domain. North Korea has a large surface navy but most of the ships are small, coastal patrol vessels that are old with outdated technology and unable to operate far from shore. Recently, however, Kim Jong Un has acknowledged this issue and vowed to increase the North’s naval capability, including possibly with tactical nuclear weapons but the future of the surface fleet is unclear.
North Korea’s submarine force is another matter. The Korean People’s Navy (KPN) consists of 70 boats, one of the largest fleets in the world, but is composed of old, noisy diesel submarines. However, Korean coastal waters are a challenging environment for anti-submarine warfare (ASW). North Korea is also working on a ballistic missile submarine capable of launching nuclear-tipped missiles that would be a serious problem for the ROK Navy (ROKN). North Korea’s land-based missiles and a future submarine-launched ballistic missile (SLBM) places ever more importance on ROK missile defense, and the Navy’s contribution through its Aegis destroyers is a crucial component to countering that threat.
Past clashes with the KPN have often occurred along a disputed maritime boundary, the Northern Limit Line (NLL). On several occasions, North and South Korean warships have fought along the NLL with deadly results. The revelation in July of a new amphibious assault battalion that could be directed at ROK islands along the NLL raise further concerns.
Illegal fishing, largely by Chinese boats has been another problem along the NLL.
Though largely a ROK Coast Guard responsibility, the Navy has also been involved in policing this trouble spot.
Maritime security concerns have increased beyond Korean coastal waters. Though China has not exerted the same level of pressure on South Korea as it has on those in the South China Sea, there are increasing signs that this may be changing. China continues to hold to its position that claims an inordinately large exclusive economic zone (EEZ) that overlaps with South Korea’s EEZ claim in the Yellow Sea. Beijing has sought to restrict ROK naval activity in the Yellow Sea within a line bounded by 124 degrees longitude. While pressing Seoul to comply with this line, the People’s Liberation Army-Navy has not abided by the marker. China has also laid out a series of buoys in the Yellow Sea that are likely an effort to monitor naval and commercial activity in the area. Lastly, the administration of Ieodo and the 2013 extension of Beijing’s air-defense identification zone to include the submerged feature is another friction point. When viewing all of these elements together, ROK officials are increasingly concerned that China seeks to limit South Korean operations in the Yellow Sea with Beijing pursuing its interests at South Korea’s expense.
Korean defense planners will also note that another regional maritime concern has been the island dispute over Dokdo or Takeshima to Japan. The ROKN conducts exercises twice a year to train for protecting this group of islets. The likelihood of Japan using force to press its claim was always remote and the recent improvement in South Korea-Japan relations will make this mission less critical.
Beyond the Asia-Pacific, South Korea has important maritime interests in global waters. The ROK economic success story is deeply rooted in international trade. Lacking in raw materials, South Korea is heavily dependent on imports to fuel its growth and with a relatively small domestic market, relies heavily on exports. Most of this trade is done on the seas so that a vital ROK interest is safe and secure global shipping lanes. Major disruptions to ocean commerce whether through state conflict or non-state challenges like piracy would have a serious impact on ROK commerce. Altogether, the interests and stakes for South Korea, from coastal to regional to international waters have increased dramatically over the years requiring a reassessment of the importance of the maritime domain to ROK security.
Dealing with this ever more complicated matrix of maritime threats, the ROK Navy can build its future force structure on two central principles: persistent presence for coastal waters and expeditionary reach for more distant seas. These two principles provide helpful guidance to grow and align the fleet to the more complicated mission sets and responsibilities in the waters near and abroad that threaten ROK interests.
Defending South Korean coastal waters requires persistent presence, and the Navy has been doing well in developing a capable naval force for this area. The ROKN has increased and modernized its coastal fleet by adding advanced PKMR [Patrol Killer Medium Rocket] and PKG [Patrol Killer Guided-missile] patrol craft in addition to new lines of frigates. ROK Aegis destroyers and their missile defense capabilities will also play a crucial role in the near seas defending against North Korea’s growing missile force with its missile defense capabilities. With its three existing DDG-III King Sejong the Great-class destroyers, the ROKN is building three Batch II Aegis destroyers to further add to its missile defense assets.
The ROKN has also made significant additions to the size and capability of its submarine force that provides important elements to South Korea’s persistent presence in coastal waters. The ROKN has completed construction of the first batch of 3 KSS-III Dosan Ahn Changho-class submarines. Built largely with indigenous technology, the submarines are diesel-electric boats that run quietly when submerged and are equipped with air independent propulsion that allow them to run longer before surfacing. These submarines are considered strategic assets since they can carry conventionally-armed SLBMs to hit targets in North Korea but are also integral to the ASW mission in Korean waters. Construction plans include two additional batches of these submarines for a total of nine KSS-III boats with later versions capable of carrying cruise missiles. When finished, the ROK submarine force will total 27 boats though this number will decrease as the older KSS-I Jang Bogo submarines are retired.
Important improvements have also been made in tactical abilities, particularly ASW, through increased exercises with the United States and other navies. The ROKN must maintain this persistent presence in coastal waters through strategy, operational skill, force development, and ROK-US alliance cooperation.
In regional and global seas, the ROKN needs an expeditionary naval force that can protect its interests in more distant maritime areas but with different vessels and capabilities than are needed for its littoral operations. South Korea will never be able to build a navy that is comparable in size, capability, and reach to the US or Chinese fleet. In addition, the ROKN does not currently have sufficient capacity for more long-term commitments and regular presence like the Cheonghae Unit off the Horn of Africa. When South Korea deployed one ship to the counter-piracy operation, it actually meant committing three vessels to the mission – while one of the Chungmugong Yi Sunshin-class DDH-II destroyers is on station off the coast of Somalia, another is on its way home from deployment, and a third is undergoing maintenance and training for the next assignment. Short-term, temporary operations such as helping with disaster relief efforts are possible but another extended mission like the Cheonghae Unit will strain the fleet.
Yet, the protection of its commercial vessels and shipping lanes are vital to the ROK economy and requires a force that can be deployed on short notice when necessary to safeguard its economic interests in distant seas. Destroyers, large-deck amphibious assault ships, and aircraft carriers with the necessary naval air wings are assets that would be useful for these tasks giving the ROKN the needed reach into other regions to protect its interests while also being useful in its home waters if needed. This is particularly the case for Aegis destroyers and the planned next generation KDDX-class destroyers which are flexible, multi-mission warships capable of distant operations and supporting a task force while also doing ASW, air defense, and missile defense closer to home. The CVX carrier program, while being an expeditionary asset would also be dual-purpose providing airpower that is less vulnerable than land-based aircraft for conflict closer to home.
Another asset to consider here is a nuclear-powered ballistic missile submarine that for South Korea would carry conventionally-armed missiles. While the ROK fleet of diesel boats are well-suited for ASW and coastal operations, a nuclear-powered submarine is less useful in near seas.
Though it has several advantages due to its endurance and longer dwell time, these benefits, along with its long-range strike capabilities, are more suited for far seas operations. Given the pressing need for coastal defense, the money for nuclear-powered submarines may be better
spent on more diesel-electric boats.
The expeditionary force must be capable and available for distant operations when needed but need not be overly large. Moreover, if a disruption to maritime security requires this type of intervention, it is likely affecting others as well so that the response will be multilateral and will not require the ROKN to act alone. Expeditionary operations will also require consideration of the necessary logistics arrangements.
ROK defense planners face difficult decisions in setting priorities based on a changing and complex security environment, budget limitations, and the South Korean demographics challenge that will impose personnel constraints for all elements of the ROK military. For the Navy, persistent presence in coastal waters and an expeditionary naval capability provides consistency at home and flexibility in far seas to deal with the increasingly complex and challenging maritime domain.
Terence Roehrig is Professor of National Security Affairs at the U.S. Naval War College. He was a Research Fellow at the Kennedy School at Harvard University and a past President of the Association of Korean Political Studies.
- Sophia Costes and Grace Jones, “The US Navy will employ autonomous vessels in a new region—but integrating the tech won’t be easy”, Atlantic Council. September 26, 2023.
- Jeffrey E. Kline, “REVAMPING FLEET DESIGN AND MARITIME STRATEGY: AN INTEGRATED NAVAL CAMPAIGN FOR ADVANTAGE,” CIMSEC, September 18, 2023.
- Steven Bancroft and Benjamin Van Horrick, “CREATING A SEA CHANGE: TF 76/3, ADAPTATION, EXPERIMENTATION, AND THE JOINT FORCE”, Modern War Institute March 01, 2023.
The opinions expressed in this article are the author’s own and do not reflect the view of KIMS.