Beyond Hormuz: Japan’s Strategic Balancing Between Iran and the United States
Introduction
Japanese-Iranian diplomacy dates back to 1880, when Tokyo’s first official delegation visited Naser al-Din Shah Qajar. Japan shifted from “quiet diplomacy” to direct Gulf engagement during the 1970s Oil Crisis, later sending special representatives to Iran after the 1979 revolution. Today, Japan’s strategic interests in Iran and the Middle East are multifaceted. Crucially, Japan relies on the Gulf for over 90 percent of its oil and gas, making safe passage and securing regional sea lanes vital to its Free and Open Indo-Pacific strategy. While aiming to maintain Eurasian connectivity, Japan also seeks to counter China’s growing regional influence. On top of that, Japanese officials have numerous times found themselves in complex situations trying to balance their relationship with Iran and the United States due to these dual dependencies. On one hand, Japan depends heavily on energy imports from the Gulf, including from Iran, and on the other, the U.S is its ‘big brother’ and ensures security for the state.
The armed conflict between the United States, Israel, and Iran created significant uncertainty in global energy and shipping markets, raising concerns about the security of the Strait of Hormuz. The strait is a vital global chokepoint that not only handles 25 percent of global crude oil, but also 33 percent of global fertilizer, gases used for semiconductor manufacturing and other critical minerals like aluminum. Asian countries are particularly exposed to any disruption in maritime traffic through the waterway as they receive 80 percent of the oil that transits through the strait. China and India get around 50 percent of their oil from there, but South Korea gets 70 percent, and Japan 93 percent. Any prolonged disruption in this strait is a matter of national security for these countries. For Japan, experts at Kiel have predicted that a prolonged closure of the waterway will not only threaten its stock market and currency, but also cost up to USD 5 billion in economic losses.
The underlying diplomatic headache emanating from this crisis is deeply familiar to Japanese leadership. In 2019, Prime Minister Shinzo Abe faced this exact challenge during the U.S.-Iran “shadow war.” Making a historic visit to Tehran to de-escalate tensions and negotiate Iranian denuclearization, Abe’s diplomatic efforts suffered a severe setback when the Japanese-owned tanker Kokuka Courageous was attacked during his stay. Despite this, he still secured a reaffirmation from Supreme Leader Ayatollah Khamenei that Iran would not manufacture, possess, or use nuclear weapons. Throughout the crisis, the Prime Minister relied on “telephone diplomacy” to keep the strait open while intentionally choosing not to join the U.S. military coalition.
Part I: Strategic Non-Intervention
Six years later, Prime Minister Sanae Takaishi found herself navigating a comparable crisis involving Iran, where she was tasked with safeguarding freedom of navigation and Japan’s economic interests while avoiding a rupture with Tokyo’s primary ally, the United States. Comparably to 2019, a few months ago President Trump called on allies of the United States to join him in a mission aimed at protecting maritime traffic and regional stability. Except, this time around, Japan seemed marked by a shifting paradigm of significantly stronger security policies.
Multiple factors point towards a more military-ready Japan in 2026. To begin with, Prime Minister Takaichi’s agenda placed the expansion of the new defense budget high on her list of priorities. Accepted in February with JPY 8.8 trillion (USD 62.2 billion), this JPY 300 billion year-on-year increase places the island into the Top 10 defense spenders globally. There were also numerous signs of improved military equipment and technology earlier this year. For example, the MSDF refitted the destroyer JS Chokai with long-range U.S. Tomahawk missiles. Additionally, the military announced an upgraded Type-12 surface-to-ship missile. Furthermore, Japan’s 2026 budget is funding the “SHIELD” system, a system that can deploy hundreds of AI-driven combat and surveillance drones across the southwestern islands. Although Japan’s expanding capabilities are typically analyzed in the context of deterring China, they fit into a wider global trend toward remilitarization and only circumstantially with the crisis in the Gulf Region.
Moreover, opposition to legalizing the Self-Defense Forces (SDF) has dropped from 53 percent in 2018 to an all-time low of 9.4 percent following Prime Minister Takaichi’s landslide victory in February 2026. Still, a divide exists between general SDF support and trust in the government to amend the constitution. Despite the 70–80 percent support for legalizing the SDF, few favor an Emergency Clause granting the government extended crisis powers. Illustrating this, in an interview with Japan Forward, Nobukatsu Kanehara, former Assistant Chief Cabinet Secretary to Prime Minister Abe, states it is time for Japan to move beyond its “nonsensical postwar shackles” and the punitive constraints imposed on its armed forces as a defeated nation. He argues that Japan has the right to exercise self-defense if a major disruption in the Strait of Hormuz severely damages its economy.
Debates rapidly emerged over deploying Japan’s Self-Defense Forces (SDF) to assist in the recent U.S.-Iran conflict. Under the 2015 Armed Attack Situation Act, collective self-defense requires an attack on an ally to pose a “clear danger” to Japan’s survival. Former PM Abe previously cited a mine blockade in the Strait of Hormuz as a concrete example of this. Despite stretching Article 9 to its limits, Abe followed precedent in 2019, declaring constitutional constraints barred Japan from U.S.-led combat operations. The question of whether the situation constituted a survival-threatening scenario arose again this March. Even though, 16 civilian merchant vessels from Thailand, Japan, and the Marshall Islands were reportedly targeted, Japanese officials swiftly stated a deployment to assist the U.S. was beyond their capacity. The only action the Self-Defense Forces (SDF) might take, only following a ceasefire, would be deploying Japan’s renowned minesweepers to the strait.
Part II: Strategic Non-Mediation
Prime Minister Takaishi deflected the multiple calls from Washington for Japan to do more during the crisis. She maintained that she had provided President Trump with a “detailed explanation” of the legal constraints on sending the Maritime SDF to the region, during a summit in March. Nevertheless, officials in Tokyo briefly considered directly mediating between Iran and the United States. Following a 25-minute phone call with Tehran, on April 8, Prime Minister Takaishi contacted the White House in hopes of brokering dialogue. However, she swiftly downplayed a formal moderating role, stating: “We have historically built relations with Iran, and the United States is our ally… while I’m not sure if we can act as mediators, we will convey our views to both sides.”
During this same phone call with Iranian President Masoud Pezeshkian, Takaishi emphasized the need to secure the safety of ships sailing through the strait and worked towards solving the matter of the Japanese national detained in Iran. She also advocated for a free and open strait. These efforts reflected Tokyo’s broader objective of reducing tensions and preserving freedom of navigation.
The Prime Minister did not force any of the United States’ messages on Iran; instead, she opted for a diplomatic push to negotiate national priorities. In the end, Tokyo chose a strategy of “soft balancing” which allowed Japan to negotiate the release of the detained Japanese national, facilitate the safe passage of some Japanese ships, and maintain its international pacifist image and domestic reputation.
Then, Japan decided to do what it does best. It worked in bilateral talks with East Asian countries to advocate for safe passage through the strait. PM Takaishi personally lobbied the leaders of the Philippines, Malaysia, and the Marshall Islands. These efforts helped secure a joint statement signed by more than 30 nations, including South Korea and Australia. Thus, though falling short of providing direct military support, Japan did everything possible to secure diplomatic backing from Asian nations.
Nonetheless, some in the government feared a potential rift in the archipelago’s relationship with Washington after not answering the calls for a coalition. These fears grew wider after President Trump’s criticism of allies: Although, the United States would have welcomed greater military participation from Japan during this conflict, Fred Fleitz (Chief of Staff for Trump 2018) has argued that Japan’s primary role lies in the Indo-Pacific rather than external conflicts. Fleitz agrees that Trump harshly criticized NATO allies, however, he also points out that Washington views Japan differently, remaining fully aware of its constitutional constraints. He states that China as well as North Korea are the priorities and maintains “American security becomes stronger when Japan becomes stronger.”
Alexander Gray (Chief of Staff 2020) affirms that the Washington-Tokyo alliance goes beyond this matter. Even if the two leaders agreed to maintain close communication to promote peace and stability in the Middle East, Gray argues that Japan’s utility lies elsewhere: “I’m not sure where Japan would fit in at this point”, Japan should “double and triple down on its capacity to act as a force multiplier and deterrent vis-a-vis China and the Indo-Pacific.” Gray highlights several steps Japan must take to become a more capable partner: raising defense spending, accelerating procurement, establishing a traditional intelligence agency, expanding defense exports, and advancing constitutional reform.
As indicated by the analyses of Fleitz and Gray, the U.S.-Japan alliance will likely weather the disparity in their respective approaches to the Iranian crisis; nevertheless, Washington’s expectations for Japanese strategic contributions are at an all-time high. There is a growing desire to see Japan increase its defense budget, achieve effective deterrence in the Indo-Pacific, and revise its constitution to formally include the SDF.
Conclusion: Balancing Strategy – Look into the Future
Japan has already made serious progress on the first two objectives listed above but the question remains: when will it take the final step toward constitutional reform?
While Japanese media headlines were dominated by the Iran crisis until mid-April, attention has since shifted toward Japan’s military cooperation with Southeast Asian countries and developments involving China. Similarly, recent talks between Trump and Takaishi reviewed the discussions in Beijing during the U.S.-China summit, with the goal of aligning regional strategies regarding Taiwan and the broader Indo-Pacific. Finally, these last few weeks there seems to be a resurgence in Japan’s efforts to promote the Free and Open Indo-Pacific and build economic security in the region. There is a strong focus on security matters on Japan’s agenda, but the Strait of Hormuz no longer seems to be a major part of it.
Once again, Tokyo has successfully navigated a period of heightened U.S.-Iran tensions, balancing its national priorities without alienating Washington. However, questions remain about the sustainability of this strategy: how long can Japan maintain this delicate balancing act? The next emergency may occur much closer to home, and when it does, Japan will have to decide whether its postwar restraints remain a source of stability or have become a strategic liability.