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'Nuclear' or 'atomic'? Gov't terminology on submarines baffles public.

Published: 13 Nov. 2025, 09:14 Updated: 13 Nov. 2025, 16:33

Defense Minister Ahn Gyu-back answers questions from lawmakers during a National Assembly defense committee meeting in Yeouido, western Seoul, on Nov. 5. [LIM HYUN-DONG]

The government has changed its terminology for nuclear-propelled submarines to atomic-propelled submarines, then back to nuclear-propelled submarines, causing confusion among the public about the government's stance on the much-debated technology.

The Ministry of National Defense said Tuesday that the government had decided to revert to the term nuclear-propelled submarine after a “government-wide discussion,” explaining that the decision was made “to use terminology familiar to the public.” The announcement came just six days after Defense Minister Ahn Gyu-back declared on Nov. 5 that the official term would be nuclear-propelled submarine.

Although they mean the same, the literal Korean translations for nuclear and atomic are haek and wonjaryeok, respectively. While the former Korean term is often used to describe nuclear weapons, the latter is more often used to describe nuclear ("atomic") power plants and thus considered less provocative. Accordingly, while the government began calling its proposed vessel a "nuclear-propelled" submarine — or haek jamsuham, shortened to haekjam — it switched to calling it an "atomic-propelled" submarine — or wonjaryeok jamsuham, shortened to wonjam — in Korean.

So when the government first formalized its plan to introduce the submarine following the Korea-U.S. summit on Oct. 29, it used the term nuclear-propelled submarine. During the expanded luncheon meeting with U.S. President Donald Trump, President Lee Jae Myung requested the supply of “nuclear fuel” and referred to the vessel as a "nuclear-propelled submarine."

Officials from the presidential office also used the term nuclear-propelled submarine during briefings about the summit’s outcome that same day.

A week later, on Nov. 5, Minister Ahn corrected the terminology at a National Assembly defense committee meeting, saying that the official term would instead be atomic-propelled submarine. When liberal Democratic Party Rep. Jung Chung-rae asked whether “the government decided to introduce a nuclear-propelled submarine but officially name it an atomic-propelled submarine,” Ahn replied, “That’s correct.”

Ahn explained that the change was made to avoid the misperception that the submarine would carry nuclear weapons. “The term nuclear submarine could make people think it is armed with nuclear warheads and cause unnecessary concern in the international community,” he said, emphasizing that the program was focused on “peaceful use” — the rationale behind the semantic shift from "nuclear-propelled" to "atomic-propelled" submarine.

President Lee Jae Myung, fourth from right, holds a summit with U.S. President Donald Trump, fourth from left, at the Gyeongju National Museum in the southeastern city of Gyeongju on Oct. 29. [JOINT PRESS CORPS]

The move appeared aimed at underlining that Seoul’s submarine project had nothing to do with nuclear weapons and was in full compliance with international nonproliferation norms. At the time, the Defense Ministry said the change reflected a “government-level decision,” not Ahn’s personal stance.

The Foreign Ministry also used the term atomic-propelled submarine in its Oct. 31 statement responding to Beijing’s expression of concern, stressing that the project involved a “conventionally armed atomic-propelled submarine” consistent with the Nuclear Nonproliferation Treaty (NPT).

But confusion deepened when the government abruptly reversed course again last Friday evening, reportedly instructing working-level Defense Ministry officials to resume using the term "nuclear-propelled submarine" as the official term.

The next morning, Minister Ahn described Korea’s defense ambitions during a televised interview, saying, “On top of Korea’s world-class shipbuilding technology, we will build nuclear-propelled submarines.” The Defense Ministry later confirmed that this reflected the new government directive.

Following the interview, the ministry also sent text messages to reporters, clarifying that Ahn had been referring to "Washington’s general support for Korea’s construction of nuclear-propelled submarines."

The U.S. Navy's Los Angeles-class nuclear-powered submarine USS Alexandria is seen arriving at the Busan Naval Operations Base in Busan on Feb. 10. Commissioned in 1991, the Alexandria, measuring 110 meters long and 10 meters wide, entered Busan to load supplies and provide crew rest, marking the submarine's first port call in Korea. [NEWS1]

As a result, the government’s terminology shifted from nuclear-propelled on Oct. 29 to atomic-propelled submarine on Nov. 5, then back to nuclear-propelled submarine on Nov. 11, sparking criticism for inconsistency and public confusion. The stated reasons for each change — “to emphasize peaceful use” versus “to use familiar terminology” — have also drawn scrutiny.

Observers say the flip-flop raises the question of whether the government no longer worries that the international community might mistakenly believe Korea’s submarines carry nuclear weapons. Some experts say the preference for "nuclear-propelled" may be politically motivated.

“The government seems to be framing the issue as ‘nuclear-propelled submarines are the completion of self-reliant defense,’ possibly to divert attention from the practical obstacles such as nuclear fuel procurement and the immense costs,” said Lee Byong-chul, a professor at the Institute for Far Eastern Studies at Kyungnam University. “Rather than relying on the political appeal of the term, the government should focus on providing accurate and realistic information to the public.”

Inside the military, the sudden reversal has caused confusion as well. The Navy, which has long referred to the project as an atomic-propelled submarine to emphasize its peaceful nature, was reportedly taken aback by the change.

In materials submitted to the National Assembly’s audit late last month, the Navy described the vessel as "an atomic-propelled submarine capable of countering maritime threats from North Korea and neighboring countries."

Disclaimer: The Korea JoongAng Daily has been using "nuclear" and "nuclear-powered" to distinguish the Korean terms haek and wonjaryeok, which have been at the center of the controversy surrounding the submarine project. However, our publication will use the term "nuclear-propelled" and "atomic-propelled" moving forward to convey a more accurate picture of the difference.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY SHIM SEOK-YONG [[email protected]]