Seoul, South Korea
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South Korea desires to be a part of the undersea naval elite – and has obtained the blessing of US President Donald Trump to do exactly that.
Having Seoul develop into the seventh nation in the world working nuclear-powered submarines – becoming a member of the United States, Russia, China, France, the United Kingdom and India – may very well be a win-win.
South Korea might extra successfully counter North Korean or Chinese strikes in the waters round the Korean Peninsula; and that may liberate the US Navy’s nuclear-powered assault subs to think about patrols in sizzling spots like the South China Sea and the waters round Taiwan.
On either side of the Pacific, constructing the vessels might imply 1000’s of high-paying manufacturing jobs, serving to the US and South Korean economies.
“For South Korea, this would be a game-changer countering North Korea’s undersea threat,” stated Yu Jihoon, a analysis fellow at the Korea Institute for Defense Analyses and former South Korean submarine officer.
Nuclear-powered subs “could transform South Korea’s role within the alliance to be a more capable security provider, so the strategic implications for the South Korea-US alliance are even more significant,” he added.
But, as is usually the case in naval shipbuilding, the satan is in the particulars.
Nuclear-powered submarines (SSNs) include many benefits. They can keep submerged for lengthy durations of time – primarily for years, if they will carry sufficient provisions for the crew – whereas most conventionally powered subs should floor for air to run diesel engines, which in flip cost their batteries for operating at depth.
They are additionally typically sooner than conventionally powered subs and are in many circumstances quieter.
Acquiring them has been a decades-long want of the South Korean authorities.
But Seoul has confronted a key roadblock: beneath a decades-old nuclear settlement with the US, it isn’t allowed to reprocess spent nuclear gas, regardless of having the expertise to accomplish that.
Korean officers have mentioned the situation with earlier US administrations, however all the time behind closed doorways.
So, when South Korean President Lee Jae Myung talked about his authorities’s decades-long want for the US to elevate the ban, throughout his open talks with Trump in late October, many had been stunned.
Then the day after Lee’s request, Trump appeared to approve it. “I have given them approval to build a Nuclear Powered Submarine, rather than the old fashioned, and far less nimble, diesel powered Submarines that they have now,” he wrote on Truth Social.
In his open request to Trump, Lee stated that he “wanted to better track submarines in the seas near North Korea and China.”
He stated the shorter submergence time of diesel-powered subs limits how lengthy Seoul’s subs can monitor these of China, which has nuclear-powered assault subs, and North Korea, which is pursuing them.
Lee informed Trump this plan, if authorized, might help Washington as it could “significantly reduce the burden on US forces” round the Korean Peninsula.
The US Navy might actually use help beneath the waves.
Speaking at a US House subcommittee listening to in 2019, the then head of US Indo-Pacific Command, Adm. Philip Davidson, gave a stark evaluation of the challenges Washington confronted.
“There are four-hundred foreign submarines in the world, of which roughly 75% reside in the Indo-Pacific region. One hundred and sixty of these submarines belong to China, Russia, and North Korea,” Davidson informed the panel.
“While these three countries increase their capacity, the United States retires attack submarines (SSNs) faster than they are replaced,” Davidson stated.
As of July 1, 2025, a US Navy web site reveals it had 49 assault subs in its fleet, which should cowl all the world’s oceans. About two-thirds of that fleet is accessible to “surge” in an emergency, the acting chief of naval operations said last April, however fewer subs are out on patrol throughout routine operations.
Many in South Korea say it’s able to constructing the SSNs. The nation’s Defense Minister Ahn Kyu-back informed a parliamentary audit on October 30 that South Korea has “already secured various conditions needed to build nuclear-powered submarines.”
Choi Il, a retired South Korean Navy submarine captain who now runs a non-public analysis institute, agrees with Ahn. “South Korea already possesses the capability to build submarines of 3,000 tons or larger,” he stated.
Choi additional famous that South Korea’s current Jangbogo-III submarines, with diesel-electric propulsion, are “structurally designed to allow a nuclear propulsion system.” But South Korean Chief of Naval Operations Adm. Kang Dong-gil informed the October audit that it might “take more than 10 years” to convert the Jangbogo to nuclear propulsion.
Experts say the hinge of any deal will likely be location: the place is the finest, most-efficient place to construct South Korean, nuclear-powered submarines?
In a subsequent Truth Social publish, Trump added that the SSNs can be constructed at the Philadelphia Shipyard, not too long ago acquired by South Korean shipbuilding and protection conglomerate Hanwha.
Later, when the reality sheet between the US and South Korea was launched, South Korea’s nationwide safety adviser Wi Sung-lac informed reporters that the discussions on the submarines had been performed on the premise that they “would be built in South Korea,” although the reality sheet had no particular point out of the manufacturing location.
“The core issue in Trump’s post was the mention of the Philly shipyard,” stated Kim Dong-yeob, South Korean navy knowledgeable and a professor at the Institute for Far Eastern Studies at Kyungman University.
“What we wanted was not simply to possess nuclear-powered submarines but to secure related technologies and achieve industrial effects through domestic construction,” Kim informed NCS.
“Building at the Philly shipyard means losing technology transfer. It is essentially no different from buying weapons built in the US.”
Hanwha Ocean, half proprietor of the Philly shipyard, disagreed with the concern and welcomed the choice. In a assertion, the firm stated that it “is ready to provide support with its state-of-the art shipbuilding technology,” and added “investments and partnerships in facilities such as the Philly shipyard will contribute to the prosperity and shared security of both nations.”
A shipbuilding trade official who’s acquainted with the matter informed NCS that Hanwha Ocean plans to introduce superior workforce coaching applications at the Philly shipyard. Hanwha Ocean’s technical capabilities designing and constructing 5 of the six current 3,000-ton diesel submarines (Jangbogo-III class) would imply there’d be no situation constructing nuclear-powered submarines at the Philly shipyard.
But nobody doubts that such work would require a very long time. Even if the plan clears congressional hurdles immediately, specialists nonetheless venture at the very least 10 years till South Korea might purchase a nuclear-powered submarine.
The Philly shipyard is being modernized by Hanwha Ocean, but it’s geared for business shipbuilding. Building subs would require further investments for a roof-covered facility and dry dock.
Considering the lack of infrastructure, particularly for sourcing the onboard nuclear reactor, US delivery knowledgeable Sal Mercogliano stated the Philly yard would probably solely deal with a part of the construct.
“We may see large modules and sections come across from Korea over to the US and then it’s really the nuclear power plant and the associated propulsion systems that are going to be done domestically here in the US because the US has a track record for the nuclear plants,” Mercogliano, a professor at Campbell University in North Carolina, stated.
US Navy submarines are constructed at two shipyards: General Dynamics Electric Boat in Connecticut, and Huntington Ingalls Industries’ Newport News Shipbuilding in Virginia. Both yards have full development schedules as the US modernizes its personal submarine fleet, so becoming new South Korean development into these services appears problematic.
Meanwhile, the US congressional approval and US Defense Department technical overview for precise implementation might additionally take time. US Secretary of Defense Pete Hegseth stated his division will “work closely” with the departments of State and Energy to fulfil the president’s dedication, as he visited Seoul days after Trump.
However, whether or not the scope of US permission will likely be restricted to gas provide or embrace nuclear propulsion expertise switch stays unclear.
While South Korea doesn’t have a nuclear-powered submarine, in October it launched the 3,600-ton Jang Yeongsil, “the world’s best diesel submarine,” according to the country’s Defense Acquisition Program Administration (DAPA).
Designed and constructed in South Korea, it was made by Hanwha Ocean.
Although it’s a typical submarine, the Jang Yeongsil is provided with lithium-ion batteries, which allow it to keep submerged and maintain maximum-speed maneuverability longer than others with conventional lead-acid batteries.
“Lithium-ion batteries, in general, compared to lead-acid batteries can be charged much faster… the other thing is that the lithium-ion batteries can contain a lot more energy for the same weight or same volume,” Thomas Shugart, a retired US Navy captain and adjunct senior fellow at the Center for a New American Security, informed NCS.
“So, maybe a submarine that before could only keep submerged for three or four days, now maybe it’s more like 10 or 12 days.”
If South Korea can domestically construct such a sophisticated sub, why does it nonetheless need a nuclear-powered one?
Retired South Korean Adm. Kim Duk-ki believes that proudly owning a nuclear-powered submarine would enable South Korea to “more efficiently” comprise Chinese and Russian submarines and floor ships in case of a conflict on the Korean Peninsula.
“South Korea needs to operate across long distances to block Chinese submarines that would come to Korean waters to support North Korea in case of war, and there could be limitations to doing that only with conventional submarines,” Kim informed NCS, emphasizing the quick pace of nuclear-powered submarines.
Shugart, nevertheless, questions South Korea’s want: “It doesn’t make a lot of sense to me from an operational perspective.”
“The primary benefit to nuclear-powered (submarines) is mainly speed, being able to go fast for a long period of time and cross long distances at a rapid clip,” Shugart stated.
But “South Korea and Japan are right there where the action is likely to be,” he continued, including that SSNs might make sense if Seoul’s intention was to perform aggressive anti-submarine warfare.
A possible South Korean nuclear-powered sub might additionally exacerbate an arms race in the area. North Korea referred to as South Korea’s pursuit of SSNs “a strategic move for its own nuclear weaponization,” regardless of Seoul clarifying that the submarine wouldn’t carry nuclear weapons.
“This is bound to cause a nuclear domino phenomenon in the region and spark a hot arms race,” North Korean state media KCNA stated.
Earlier this 12 months, Pyongyang revealed its personal nuclear-powered submarine. It’s beneath development with the goal to end it by the finish of 2025, in accordance with the five-year weapons improvement plan Kim Jong Un introduced in 2021.
For China’s half, Foreign Ministry spokesperson Guo Jiakun urged warning and restraint.
“China hopes that both South Korea and the United States will earnestly fulfil their nuclear non-proliferation obligations and do things that promote regional peace and stability, not the opposite,” Guo stated.
Geopolitical repercussions, together with Beijing’s backlash, are amongst the most regarding elements in accordance to professor Kim of Kyungman University.
“It is essentially declaring that South Korea would participate as the frontline spear and shield in the US-led China containment strategy,” Kim added. “Whether we can withstand the potential economic retaliation from China needs to be analyzed.”