According to the Chosun Ilbo, South Korea’s leading national-conservative newspaper, the agreements between Donald Trump and Lee Jae-myung—negotiated on the sidelines of the late-October Asia Pacific Economic Cooperation summit in Busan—represent Seoul’s first step
towards becoming a fully autonomous nuclear State
, capable of building and operating nuclear reactors and producing nuclear fuel. It was a historically significant
event.
The agreement is part of a broader one concerning the commitment by Seoul to invest $350 billion in the US, including $150 billion in the shipbuilding sector. This commitment was matched by Trump’s green light
for South Korea’s ambition to build a fleet of nuclear-powered submarines, or SSNs.
National-progressive ambitions for national autonomy
As noted by the newspaper Hankyoreh, linked to the Democratic Party, which currently holds the presidency and a parliamentary majority, this has long been on the wish list of progressive governments
: for at least 30 years, thanks in part to assistance from other countries, Seoul has been developing the technologies necessary to build nuclear-powered vessels. But the American veto on allowing fuel enrichment and processing has frustrated this ambition. This has kept Seoul in a position of asymmetry with Tokyo, which, since 1988, according to Chosun, has been enriching and reprocessing nuclear fuel, and separating plutonium. This is an essential element of Japan’s nuclear threshold status, i.e., its capacity, if necessary, to develop a national deterrent.
The disparity between Japan and Seoul dates back to the late 1970s, when Washington imposed the cessation of the clandestine nuclear programme initiated by President Park Chung-hee in 1972-73. The nuclear submarine programme was authorised by the progressive presidency of Roh Moo-hyun, in office from 2003-2008, with the aim of strengthening Seoul’s defence autonomy
. The Catholic Moon Jae-in, in office from 2017-2022, was in favour of equipping these platforms with new ballistic missiles with conventional warheads but with a payload capacity of two tonnes. The debate on the possible development of a national nuclear arsenal has often been raised by the national-conservative right, as is also the case in Japan. However, Kim Dae-jung, a Catholic and president from 1998-2003, who was exiled to Tokyo during the military dictatorship in South Korea, was also in favour of a national nuclear deterrent
.
Fears and hypotheses of a Gaullist path
in Asia
Zachary Keck is an expert on non-proliferation policy and former advisor to the US Congress Armed Services Committee. According to him, since the 1960s, under the Kennedy and Johnson presidencies, Washington has feared the possibility that a Gaullist path
might take shape among its Asian allies: the creation of national nuclear deterrents based on the French model which, in the absence of a regional alliance such as that of NATO in Europe, would open the door to possible neutralism
(Atomic Friends, 2022).
The US, he points out, cannot control who runs allied countries
: even if a nuclear programme were to be initiated, for example in Tokyo, by a strongly pro-American leader
, there is no guarantee that a future leader who may be hostile
would not use nuclear capabilities to undermine the alliance
or to pursue policies incompatible with US interests. There is also the risk that such capabilities could be used to influence Washington’s positions, in the manner of Israel, whose nuclear opacity
has been a serious source of friction for American non-proliferation policies
, especially in relation to Japan and Germany’s accession to the Non-Proliferation Treaty (NPT). Essentially, for Keck, Israel’s deterrent acts as an informal security treaty, guaranteeing Washington’s support for Tel Aviv’s qualitative military edge
. Israel’s capacity to militarily confront an Arab military coalition
on a conventional level prevents it from being forced to use its nuclear deterrent
.
According to Keck, in the current Trump administration, Deputy Secretary of Defence Elbridge Colby is part of the so-called relativist
camp: even while needing to uphold its non-proliferation policies, Washington would not be hostile to the emergence of a Japanese and South Korean nuclear deterrent if geopolitical circumstances
led the respective political leaderships to consider them necessary. The United States, it seems, could work to ensure that such deterrents became complementary to its extended deterrence guarantees, as was the case with the Franco-British ones. The so-called pessimistic
camp, to which Keck belongs, fears a nuclear domino effect
that would not be limited to the region, and instead favours supporting the conventional rearmament of US allies, integrated into America’s forward-presence posture in Asia, whose fundamental anchor is Japan.
MASGA
and AUKUS-lite
Trump’s agreements during his Asian tour secured a $20 billion annual investment from Seoul in the American economy, particularly in support of the shipbuilding sector, through the MASGA (Make American Shipbuilding Great Again) initiative. The shipyards acquired by the Koreans in the US are expected to be modernised and receive orders for the production of ships or components for the US Navy. As regards Tokyo, in addition to signing an agreement to create a supply chain for rare earths and critical materials essential for electronics production, Trump is said to have obtained a series of expressions of interest
from big economic groups for investments in American energy and IT infrastructure. According to The Japan Times, the submarine agreements with Seoul are the result of private talks
between Trump and Lee, but the American president would like Seoul to finance the construction of two Virginia-class SSNs for the US Navy at no cost
. In other words, a gift. Other observers speak of an AUKUS-lite
agreement, referring to the agreements signed between the US, the UK, and Australia in 2021 for the supply of SSNs to Canberra, with production shared between American and Australian shipyards.
For Michael Green, a former NSC official in the Bush administration in the early 2000s, as imposing as Trump’s figure may be
in the US political landscape, a series of posts on ‘Truth’ are not official US government policy
. Both the transfer of classified propulsion technology and the revision of the nuclear cooperation agreements defined in 2015 will require the consent of various voices within the administration, from the State Department to the Departments of Defence and Energy. But also from Congress, which Trump may struggle to convince, especially if the Democrats regain a majority after 2026. Furthermore, according to Green, as in the agreement with Australia, Seoul’s SSNs would be integrated into the combined deterrence
of Washington and its allies towards China. This would represent a constraint on Seoul’s ambitions for autonomy.
Formulas for minimum deterrence
in Tokyo
For its part, Seoul is offering to contribute to American shipbuilding capacity, which has been in sharp decline for decades. However, it would like to produce the submarines in its own shipyards and according to its own designs. Military sources say that the modular reactors designed by Hyundai for container ships are ready
and are apparently more advanced than those of Virginia-class submarines. South Korea has already developed vertical launch systems
for its own surface missile launchers.
According to the Hankyoreh, the agreement is based on an exchange: Trump is using tariffs as blackmail
to obtain investments, but is opening the door to Seoul’s nuclear ambitions. Viewing America First
politics as a manifestation of Washington’s relative decline, the other side of American unilateralism is the pursuit of offshore balancing
, i.e., placing a greater burden on allies to maintain regional balances
. By this logic, Seoul should obtain its SSNs so that it can act as an autonomous middle power
in support of the regional balance.
Several commentators in Seoul have pointed out, however, that all powers with nuclear-powered submarines combine them with a nuclear naval deterrent
. Conventional armament alone would make them less useful in deterring Pyongyang. For Wang Son-taek, diplomatic correspondent at The Korea Herald, pursuing a nuclear submarine without nuclear weapons is a rational and defensive measure, not an aggressive one
. Falling under Seoul’s drive to reinforce its conventional capacities, these submarines would complement, rather than contradict
, American extended deterrence. But, above all, if Seoul wanted to acquire nuclear weapons, it would end up accelerating the military normalisation
of Japan.
This thesis has been explicitly raised by the Yomiuri Shimbun, Japan’s leading daily newspaper, which argues that the Trump-Lee agreement could bring about a drastic change in the Asian security environment
and influence the Japanese debate on the possession of its own SSNs
. This hypothesis has shaped the programme of Tokyo’s coalition government led by Sanae Takaichi. In various speeches to the National Diet, the prime minister has hinted not only at possible Japanese military intervention in the event of a conflict in Taiwan, provoking a reaction from Beijing, but also at a possible revision in 2026 of the Three Non-Nuclear Principles—neither possess nor manufacture nuclear weapons, nor permit their introduction into Japanese territory—adopted by Tokyo in 1967. According to the Sankei Shimbun, an Osaka daily newspaper and voice of the nationalist right, revising the Three Non-Nuclear Principles is Prime Minister Takaichi’s personal position
; while she is in favour of upholding the first two, which are fundamental to Japan’s commitment
to the NPT, maintaining the third could mean potentially weakening American nuclear deterrence in a crisis
.
Since the Korean War in 1950, as Japanese historiography recalls, supporting non-introduction has represented for Tokyo a gesture of [domestic] political reassurance
. Yasuhiro Nakasone, prime minister during Japan’s rearmament in the 1980s, did not consider the three principles—a self-imposed declaration—to be in contradiction with the development of a minimal deterrence
based on weapons with one third of the power of those employed on Hiroshima
. Already under Junichiro Koizumi’s government, Tokyo defence officials believed that cruise missiles—such as Tomahawks—with a range of a thousand kilometres, carried on submarines and AEGIS-class destroyers, could represent a credible small nuclear deterrent
(Ryuji Hattori, Fighting Japan’s Cold War, 2023; T. Yoshihara and J. Holmes, Strategy in the Second Nuclear Age, 2012).
On a strategic level, according to several analysts, reaffirming that Japan is maintaining the three principles is an indirect way for Tokyo to say that they are not immutable
. Meanwhile, Japan continues to strengthen those conventional instruments that, if necessary, could provide it with a deterrent force
.
Lotta Comunista, November 2025