Commentary: What South Korea’s belated participation in the ‘Hormuz coalition’ reveals
President Donald Trump’s call for US allies to send ships to the Strait of Hormuz is a test for South Korea, says RSIS’ Jaehan Park.
Members of civic groups hold signs against the US and Israel attacks on Iran near the US Embassy in Seoul, South Korea, Apr 1, 2026. (AP Photo/Lee Jin-man)
SINGAPORE: Washington has been in a diplomatic back-and-forth with its disgruntled allies over the Strait of Hormuz. Iran’s blockade of the waterway has disrupted fuel supplies, with Asian countries bearing the brunt because of their dependence on Middle East oil.
On Mar 14, United States President Donald Trump called on countries, including US allies Japan and South Korea, to send ships to help reopen the Strait of Hormuz.
Despite initial resistance, seven countries issued a joint statement on Mar 19 expressing their “readiness to contribute to appropriate efforts to ensure safe passage through the Strait”.
Japan was a signatory of that statement, but South Korea was not. While Japanese Prime Minister Takaichi Sanae met Mr Trump in Washington, affirming that Tokyo would cooperate on achieving peace and stability in the Middle East, Seoul has appeared more circumspect. It only spoke out later, joining more than 20 countries in condemning Iran’s closure of the Strait of Hormuz.
REASONS FOR SEOUL’S RELUCTANCE
There are various reasons for Seoul’s reluctance. The first is domestic politics. There will be local elections in South Korea in June – including the mayorship of Seoul, which will be the bellwether for President Lee Jae Myung’s popularity.
If South Korea were to send naval forces to the Strait and it resulted in casualties, there would be huge blowback, potentially derailing Mr Lee’s wide-ranging policy agenda.
In contrast, Japan’s ruling Liberal Democratic Party (LDP) just secured a supermajority in February, solidifying Ms Takaichi’s position. Although her approval rating has dipped slightly since, this is likely due to economic issues. Her recent summit with Mr Trump was seen largely as a success, notwithstanding his offhand reference to Pearl Harbour.
Second, some Korean commentators have questioned the lawfulness of the US attack on Iran. They argue that Seoul should not send its young men and women into harm’s way, especially when Washington’s casus belli is unjustifiable.
Notably, these commentators are coming mostly from the progressive side, Mr Lee’s political base. It is difficult to find similar criticism in Japanese newspapers of conservative leaning, where Ms Takaichi belongs.
The third and most important – yet often unnoticed – reason comes from South Korea’s and Japan’s divergent strategic priorities, stemming from their geographies.
Despite being a key regional ally, South Korea has been reluctant to participate in US efforts to deter China, due to deep economic ties and the potential for Beijing to mediate inter-Korean affairs. A geostrategic land power, Seoul also has to prioritise its defence against North Korea, which poses an existential threat.
In contrast, Japan is an insular nation dependent upon sea lanes, and feels more threatened by China’s maritime expansion. Aligning closely with Washington, therefore, remains the best way to guarantee Tokyo’s security.
Although Tokyo’s deployment of the Self-Defense Forces to the Strait of Hormuz will be constrained by both its post-war constitution (specifically Article 9) and public opinion, it is taking a more proactive stance in support of Washington.
BROADER IMPLICATIONS FOR SOUTH KOREA
Notwithstanding Seoul’s hesitations about the Iran war, it faces broader implications from changing US policy on Asia. As the recent National Defense Strategy laid out, America’s allies, including South Korea, will have to take “primary responsibility” for its own security as Washington prioritises homeland defence and deterring China.
In effect, this means Seoul will have to expand its geographic scope beyond the Korean Peninsula and participate in Washington’s gambit to check Beijing if it wants to remain a core US ally. Yet this entails the risk of being caught in the intensifying US-China rivalry. In addition, too much involvement in distant places might weaken deterrence on the Korean Peninsula.
The alternative is to take on a larger and more autonomous role for national defence, epitomised by the discussion on the transfer of wartime operational control. This requires Seoul to meet certain conditions, including acquisitions of additional military capabilities.
The problem is that such a move might destabilise the region. Seoul’s development of conventional counterforce to deter Pyongyang independently might elicit an arms race, destabilising the Korean Peninsula. Likewise, its pursuit of nuclear-powered submarines was met by Beijing’s displeasure.
Although Seoul is not facing the binary choice yet, it will likely come under increasing pressure in the coming years. Mr Trump might be mistaken about certain things, but the “Hormuz coalition” is certainly a test for Seoul’s value to Washington. Between a rock and a hard place, South Korea’s political leadership will have to be more prudent and creative in the age of great-power competition.
Jaehan Park is an Assistant Professor at the S Rajaratnam School of International Studies (RSIS) at Nanyang Technological University and a Fellow at the Edwin O Reischauer Center for East Asian Studies at the Johns Hopkins School of Advanced International Studies (SAIS).
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