Senior defense ministry official Won Chong-dae confirmed the timeline during a cabinet meeting on Tuesday.
“If we secure the submarine fuel through consultations with the United States and enter the construction phase in the late 2020s, we expect to launch the lead vessel by the mid to late 2030s,” Won told ministers.
He emphasized that South Korea already possesses world-class design and construction capabilities for conventional submarines.
The announcement comes days after US President Donald Trump said he had given ally Seoul a green light for the project.
Trump claimed on Truth Social that Seoul would manufacture its nuclear-powered submarine in “the Philadelphia Shipyards, right here in the good ol’ USA.”
Seoul has not commented on Trump’s remarks suggesting the submarine would be built on US soil.
Won, however, stated it was “feasible to construct a nuclear-powered submarine with our own technology.”
A South Korean presidential aide confirmed Seoul had sought Washington’s “authorization for the raw materials” and received approval, AFP reporyted.
The Philadelphia shipyard mentioned by Trump has been run by South Korea’s Hanwha Ocean since last year.
Media reports indicate the facility lacks the necessary equipment for building nuclear-powered submarines.
Hanwha Ocean announced a USD 5 billion investment in the shipyard in August as part of Seoul’s commitment to supporting US shipbuilding growth.
Pentagon chief Pete Hegseth praised South Korea’s “incredible shipbuilding industry which we look forward to partnering with a lot more.”
The developments occur amid heightened tensions with North Korea, which has repeatedly declared itself an “irreversible” nuclear state.
Pyongyang dismissed Seoul’s hopes for denuclearization as a “pipedream” which “can never be realized.”
Defense Minister Ahn Gyu-back reaffirmed that denuclearization of the Korean Peninsula “remains an unwavering commitment.”
He ruled out South Korea ever possessing nuclear arms itself.