Japan's Existential Dependence: The Country That Cannot Afford a Single Month of Closure
Japan imports approximately 90 percent of its energy. It has no significant domestic fossil fuel production. Its nuclear power sector, which once provided a substantial share of electricity generation, has been operating at sharply reduced capacity since the Fukushima accident of 2011, with only a portion of the pre-accident reactor fleet returned to service. The Gulf supplies the majority of Japan’s crude oil, and Gulf LNG — primarily from Qatar — supplies a substantial portion of its natural gas. There is no combination of alternative energy policies or supply source diversification that changes the fundamental arithmetic on the timescale of months. Japan’s dependence on Hormuz is existential in a way that is not hyperbole.
The 90-day reserve requirement that Japan’s government maintains — strategic petroleum reserves equivalent to approximately three months of import cover — was designed explicitly for Hormuz disruption scenarios. The reserves are held in government tanks and in commercial storage, distributed around the country’s coastline to facilitate distribution to refineries and power plants. The management of these reserves involves continuous planning and periodic exercises. The government’s assumption is that a closure short of ninety days can be managed without industrial production disruptions reaching a scale that becomes politically unmanageable. A closure exceeding ninety days has no good answer in the current supply structure.
The political dimension of Japan’s Hormuz vulnerability shapes its foreign policy in ways that American analysts sometimes find frustrating. Japan has been reluctant to take hard lines on Iran that would jeopardize the bilateral relationship — it maintained informal diplomatic contacts with Tehran through periods when American pressure was most intense, and it imported Iranian crude until sanctions compliance requirements left it no alternative. The reluctance to antagonize Iran is not ideological sympathy. It is the rational behavior of a country that cannot afford to add Tehran to its threat list when its energy supply chain runs through Iranian coastal territory.
The same logic applies to Japan’s relationships with all Gulf producers. Tokyo maintains carefully calibrated relationships with Riyadh, Abu Dhabi, Kuwait, and Qatar simultaneously, avoiding the kind of overt alignment with any single Gulf power that would create political risk with others. Japanese diplomacy in the Gulf is energy diplomacy with a diplomatic superstructure attached. The long-term purchasing agreements, the investment in Gulf oil and gas infrastructure, the development assistance programs in Gulf states — all of these are ways of embedding Japan’s supply security into bilateral relationships that are harder to disrupt than pure spot market purchases.
The Ukraine-Russia war demonstrated something important about Japanese energy vulnerability that is directly relevant to Hormuz. When European gas markets were disrupted and LNG cargoes were redirected to higher-priced European buyers, Japanese LNG importers found themselves competing for flexible supply in a global spot market that they had previously been able to treat as a secondary source of incremental supply rather than a primary supply mechanism. Long-term contracts protected a significant portion of Japanese LNG supply. The margin that had been expected to come from flexible spot purchases became expensive or unavailable. The lesson reinforced the value of long-term contracts and the danger of assuming that spot market access provides resilience against supply shocks.
Japan’s military posture in the Gulf is constrained by its constitutional framework and by the political sensitivity of overseas military operations in Japanese domestic politics. Japan Self-Defense Force vessels have participated in anti-piracy operations in the Gulf of Aden under a legal framework specifically designed for that mission. Their participation in escort or combat operations in the strait itself would require legal changes and political decisions that successive Japanese governments have treated as a threshold they are not prepared to cross. Japan is defended by American naval power in the strait. It has no independent capacity to change the security conditions that determine whether its supply reaches it.
This is the cleanest possible description of strategic dependence: a country whose national economy runs through a body of water it cannot defend, held open by an ally whose political commitment to that mission is not unconditional.