During the Eighth Workers’ Party Congress in North Korea in January 2021, the country’s leader Kim Jung Un announced plans for further developments of submarine-launched ballistic missiles (SLBM) and nuclear submarines.

Kim added that the country has been showing some successful examples in building such deadly weapons and submarines since the Seventh Congress held in 2016.

Shortly after this year’s congress, South Korean media outlets started to ask their government why it does not introduce nuclear-powered submarines to counterattack the potential threats from North Korea.

Dong-A Ilbo, one of the most-read newspapers, published a commentary that suggested the country needs to make a nuclear-powered submarine soon to maintain the status quo of the power balance in the Korean peninsula. 

The commentary, however, stated that the US may not give consent to develop such submarines because the ROK-US Atomic Energy Agreement states that South Korea cannot use US-produced uranium materials for military uses.

Experts said that it is not yet clear if South Korea is currently building a nuclear submarine, because such information is classified, but they clarified that the country may not require approval from the US to build a nuclear submarine if they are not using US technology. 

Shrouded in secrecy 

South Korea previously tried to build a nuclear-powered submarine under President Roh Moo-hyun’s administration. The plan to build three nuclear-powered submarines by 2020, dubbed the 362 Plan, was first introduced in 2003. 

However, a year later, when a reporter made this highly classified plan public, it had to be canceled. 

In a presidential debate in April 2017, then-candidate Moon Jae-in said that “the country now needs to have a nuclear-powered submarine.”

Last August, the South Korean Army indeed confirmed that it is planning to build a 4,000-ton submarine with a nuclear-powered engine. However, there are no updates since then, despite the huge attention from the media, and it is not even clearly known if the government is working on it.

“We wouldn’t be able to tell whether the government is actually developing a nuclear-powered submarine or not, because the information is highly classified,” Lee Jeong-ik, a professor of Nuclear and Quantum Engineering at Korea Advanced Institute of Science and Technology, told Maritime Fairtrade.

“There is no supporting evidence available to claim that the South Korean government is working hard to build a nuclear submarine, either.”

Why South Korea needs a nuclear submarine

Prof Lee said that nuclear submarines will be a huge asset to the military.

“Nuclear submarine is a strategic weapon that outperforms (other military ships) in the long run,” he said. “The military will be able to use it for many purposes, for example, it can work as part of the early warning system.”

He adds that having nuclear submarines will be the only measure that can counter and monitor North Korea’s SLBMs.

“All conventional and nuclear submarines from North Korea should be monitored, as either of them can carry nuclear weapons,” Prof Lee said. 

“As far as I know, there is no surveillance method that is better than nuclear-powered submarines because they can monitor without being noticed [by the enemy] while retaining defensive ability. 

“The various methods of sky surveillance, both in South Korea and the US, are not a good choice (compared to nuclear submarines), because they are relatively not effective when the weather condition deteriorates.”

Prof Lee also stressed that there is a difference between nuclear weapons and nuclear submarines, as their purposes can be completely different.

“Many people have the misconception that nuclear submarines will necessarily be carrying nuclear weapons. But an increasing number of nuclear submarines [operated outside of South Korea] are not carrying any nuclear weapons these days. 

“Just because its engine is powered by nuclear energy does not mean that the submarine will carry nuclear weapons too.”

Using homegrown technology

The government would indeed need the consent of the US to make a nuclear submarine if the country uses the conventional US technology of uranium enrichment. South Korea is not allowed to utilize uranium enriched to 20 percent for military purposes. 

However, Prof Lee stated that South Korea do not need the US’ consent if they utilize domestic technologies or cooperate with other countries that are independent of American influence. 

“The fuel used for nuclear submarines ranges from uranium with lower-level of enrichment to highly enriched uranium.  South Korea will use the former type of uranium produced at domestic nuclear reactors, which will leave no room for criticism from the global community.”