On October 29, US President Donald Trump revealed has announced That the US government has given South Korea permission to build a nuclear submarine on American soil.
Story by Ethan Gosro, additional reporting by Yunhyuk Cha.
The announcement was made after a meeting with various Asian heads of state, including South Korean President Lee Jae-myung, in Gyeongju, South Korea. Trump’s additional post on Truth Social detailed that the submarines will be built on U.S. soil at a Philadelphia shipyard that was acquired by Korean defense firm Hanwha in the late 2024.
Subsequently, the construction of nuclear submarines marks a deviation from previous efforts, as previous South Korean submarine construction had focused primarily on conventionally powered submarines. Correspondingly, South Korean nuclear submarine construction projects have been in limbo for some time as the US did not give tacit approval until President Trump’s statement.
“Our (US and South Korea) military alliance is stronger than ever and on that basis I have given them approval to build nuclear powered submarines.”
United States President Donald Trump via Truth Social Post
Although the Philadelphia shipyard where construction will take place is not currently equipped to handle the construction of nuclear submarines (only commercial vessels have been produced), Hanwha has reportedly invested an additional $5 billion in modernization and preparation. Despite this, there has been a lack of any concrete agreement regarding plans for the development of the shipyard and construction of submarines and there has been no official signature from the South Korean side.
These agreements are the culmination of a long-standing desire for nuclear-powered submarines expressed by the South Korean government and military. navy news As noted earlier, subsequent efforts for nuclear submarines have arisen from acute operational needs for deterrence and deterrence against neighboring countries such as North Korea, China, and Russia.
At the audit of the National Assembly’s Defense Committee on the 30th, Chief of Naval Operations Kang Dong-gil said, “The start date of the nuclear-powered submarine program has not yet been decided, but once started, it will take more than 10 years,” he said, adding, “Its displacement is expected to exceed 5,000 tons.”
Defense Acquisition Program Administration (DAPA) Commissioner Seok Jong-geon also said, “Looking at the cases of advanced countries, it generally takes about 10 years to build a nuclear-powered submarine,” Add, “If we combine our capabilities, it can be shortened to some extent.”
Minister of National Defense Ahn Kyu-baek, when asked about the scale of the planned nuclear-powered submarine acquisition, replied, “This will need to be discussed with the Navy, but I think at least four submarines will be necessary.”
Potential designs and past experiences
Currently, South Korea operates 3 classes of conventionally operated submarines, the Jang Bogo-class (KSS-I), the Sohn Wonil-class (KSS-II), and the Dosan Ahn Changho-class (KSS-III). The KSS-I and KSS-II submarines are Korean-built derivatives of the German Type 209 and Type 214 designs, with 9 boats per class in ROKN service.
KSS-III is the latest submarine design to enter service, being the first fully indigenous design to be built in this category. There are 3 Batch 1 KSS-III submarines currently in service. The first 2 boats of the batch were launched a week ago,
Accordingly, the KSS-III offers a significant capability increase over previous South Korean submarines, including an improved power plant, improved sonar, new torpedoes and K-VLS cells for more strike options with Batch 1 and 2 having 6 and 10 K-VLS cells respectively. These improvements have been allowed through greater tonnage, with the Batch 1 boats expected to be 3,750 tonnes submerged, while the Batch 2 boats are expected to be even heavier.
Given its modernity and Korean architecture, the KSS-III has previously been looked at for a possible upgrade from its conventional diesel electric/air independent propulsion power plant to a nuclear reactor. navy news This concept has already been reported on, with it offering significantly increased endurance, power output capabilities and speed compared to its conventionally powered brethren.