President Donald Trump is likely to raise the Strait of Hormuz when he meets Japanese Prime Minister Sanae Takaichi, as Washington presses allies for help in a conflict with Iran that has intensified over the past three weeks. South Korea faces similar pressures and legal questions as the US seeks support for operations tied to continued disruption in the strait.
Earlier this week Trump publicly urged the United Kingdom, China, France, Japan and South Korea to dispatch warships to the Strait of Hormuz, which has been effectively closed since US and allied strikes on Tehran began on March 28. He later softened his stance on social media, saying the US no longer needs or wants NATO countries’ assistance and that Japan, Australia and South Korea were not obliged to help. Still, allied capitals report significant pressure to respond.
When Trump hosts Takaichi at the White House, officials expect the topic of naval contributions to be on the agenda. Observers note Japan’s heavy dependence on Middle Eastern energy supplies and the advanced capabilities of its Maritime Self-Defense Force make Tokyo an obvious candidate for US requests. Japan has already tapped strategic oil reserves to blunt supply disruptions; roughly 70 percent of its oil from the Middle East transits the Hormuz corridor.
Tokyo’s pacifist constitution constrains deployments by the Self-Defense Forces. Legal grounds for action generally include direct attack on Japan, clear threats to national survival, or collective self-defense of allies under narrowly interpreted conditions. Takaichi has told lawmakers Tokyo is studying what legal options exist to protect Japanese vessels and interests, while any deployment remains hypothetical.
Analysts say Japan could contribute in ways that avoid direct combat roles. Stephen Nagy, a professor at International Christian University in Tokyo, suggested Tokyo add legally justifiable capabilities such as mine-clearance, fleet refuelling, logistics support or enhanced maritime domain awareness rather than sending combat ships into action against Iranian proxies.
Seoul confronts comparable dilemmas. As a treaty ally dependent on Middle Eastern oil, South Korea has been hit at home by rising fuel costs; the government imposed a domestic fuel price cap for the first time since the 1997 Asian financial crisis. Lawmakers have urged caution about committing military assets to the Middle East.
Retired lieutenant general In-Bum Chun said it remains unclear whether South Korea’s Mutual Defense Treaty with the United States would extend to operations in the Strait of Hormuz. Seoul must balance any support for Washington against its need to sustain credible deterrence toward North Korea. Media reports that the US is weighing redeploying some THAAD missile assets from the Korean Peninsula to the Middle East underscore how repositioning forces could have domestic security and political consequences.
Chun also noted South Korea already has a naval vessel on station in the Middle East and emphasized the practical stakes: roughly 70 percent of Korea’s oil imports move through the Hormuz route, so freedom of navigation has direct economic implications. Any final decision will require weighing allied obligations, domestic legal limits, energy security and the imperative to deter threats from the North.