On February 28, the Iran-U.S. war began. Despite ongoing negotiations between the United States and Iran at the time, Israel and the U.S. launched a barrage of attacks, and Iran retaliated across a wide area, including Israel and the Gulf region. In the Strait of Hormuz, attacks on commercial vessels, heightened vigilance against mines and drones, traffic control measures, and a U.S. maritime blockade of Iran combined to impose severe constraints on shipping routes that are vital to global energy transportation. Even in late September, traffic through the strait had not returned to prewar levels, and the crisis had yet to be fully resolved.
Against this backdrop, Japan can use the Iran war to reexamine its security framework, with particular attention to preparations for a contingency involving Taiwan. The Iran war has raised many issues, but two are especially important for Japan. The first is how to evacuate Japanese nationals and travelers when a crisis begins sooner than expected and civilian transportation networks suddenly cease to function. The second is how Japan can help ensure the safety of maritime traffic while avoiding becoming a direct party to the conflict. Both expose gaps in the institutional arrangements Japan has developed with a Taiwan contingency in mind.
Evacuating People from a Sudden Crisis
The first lesson of the Iran war is that the traditional approach of waiting until a crisis escalates before evacuating people is no longer sufficient. Even before the outbreak of hostilities, the Japanese government had warned of the deteriorating situation in Iran and encouraged Japanese nationals to leave early. Once the fighting began, however, it became necessary to confirm the safety of Japanese nationals and assist with their departure not only in Iran but also across neighboring areas, including Israel, Qatar, Bahrain, and the United Arab Emirates.
In March, the Japanese government supported multiple overland evacuations from Tehran to Azerbaijan and also assisted Japanese nationals in Gulf countries with their return home. Importantly, these evacuations were not carried out solely by Self-Defense Forces aircraft or charter flights; they relied on a combination of overland routes, commercial aviation, and transit through third countries.
An even larger problem was the temporary degradation of airports and airspace across the Gulf, including major hubs such as Dubai, Abu Dhabi, and Doha. Dubai is not simply one airport in the Middle East; it is one of the world’s leading aviation hubs linking Asia with Europe and Africa. Disruption there complicated movement not only for people evacuating Iran and Israel but also for travelers and foreign residents throughout the Gulf. The experience demonstrated once again that a crisis may not remain confined within the borders of one country and can quickly engulf regional transportation hubs.
This lesson applies directly to a Taiwan contingency. In peacetime, large numbers of Japanese nationals are in Taiwan for tourism, business, study, and long-term assignments. Once hostilities begin, not only Taiwan’s airports and ports but also the surrounding airspace and waters could become dangerous. Transportation in Hong Kong, coastal China, Okinawa, and the Sakishima Islands could also be affected. In other words, a plan designed only to move Japanese nationals out of Taiwan would be insufficient. Japan must prepare for a scenario in which multiple transportation nodes across East Asia become unavailable at the same time.
Within Japan, civil protection plans to evacuate residents and tourists from the Sakishima Islands to Kyushu and Yamaguchi have become increasingly concrete, with field exercises scheduled for fiscal year 2026. This is an important development. Yet civil protection planning primarily concerns the evacuation of people inside Japan. By contrast, the evacuation of Japanese nationals from Taiwan, Hong Kong, coastal China, and other overseas locations spans several frameworks, including consular assistance by the Ministry of Foreign Affairs, transportation under the Self-Defense Forces Act, and the securing of civilian transportation. If domestic evacuation and overseas evacuation occur simultaneously, Japan would still face the unresolved question of how to allocate aircraft, ships, airports, and ports between the two missions.
The lesson from the Iran War is not simply that Japan should increase the transport capacity of the Self-Defense Forces. Moving tens of thousands of people within a short period ultimately depends on cooperation with commercial airlines, shipping companies, airports and ports, and third countries. Japan therefore needs, in peacetime, to identify which civilian services could be maintained during a crisis, which third countries could serve as evacuation hubs, and which ports could be used if air routes were closed.
Plans must also address how to provide shelter, food, communications, and medical care for those who cannot be evacuated immediately. An evacuation plan cannot consist only of a plan for getting people out; it must also include a plan for keeping them safe until evacuation becomes possible.
Ensuring Safe Navigation Without Becoming a Party to the Conflict
The second challenge is how to ensure the safety of maritime traffic. During the Iran War, the Strait of Hormuz was not completely closed, but normal commercial navigation became extremely difficult because of the risk of attacks on and seizures of merchant vessels, heightened vigilance against mines and drones, Iranian traffic control measures, and the U.S. blockade of Iran.
In June, the United States and Iran reached a memorandum of understanding that included the reopening of the Strait of Hormuz, and the Japanese government also called for the early restoration of free and safe navigation. Yet even in late September, traffic through the strait remained well below prewar levels.
On September 22, Iran indicated that it was prepared to reopen the strait quickly if the United States eased military pressure and lifted its blockade of Iranian ports. This, in turn, shows that as of late September, the restoration of safe navigation remained a matter of diplomatic and military negotiation.
This raised a further question: who should be responsible for ensuring safe navigation? If the United States, as a party to the conflict, leads convoy escorts or other maritime operations, participating states are more likely to be perceived as having been militarily incorporated into the U.S. side. Yet civilian shipping cannot simply be left exposed in dangerous waters.
European states have therefore sought arrangements that would protect freedom of navigation while maintaining a degree of distance from U.S.-led operations. In September, France was reported to be considering a United Nations Security Council resolution for an international mission to ensure safe navigation through the Strait of Hormuz. Such an approach can be understood as an attempt to distinguish, as far as possible, alliance military operations from the protection of maritime traffic as an international public good.
A similar dilemma would arise in a Taiwan contingency. If the Taiwan Strait and surrounding waters became dangerous, maintaining maritime traffic would be a major economic and security concern for Japan. Yet the threshold for participation would be extremely high if measures to protect shipping could immediately lead to armed conflict with China. What is needed is an institutional distinction, to the greatest extent possible, between joining combat operations and supporting the safe navigation of civilian vessels. Japan should therefore clarify in advance options that are not integrated into the use of force, including post-ceasefire mine clearance, information sharing, sea-lane monitoring, rescue of vessels in distress, and cooperation with escort frameworks led by third countries.
This issue is also related to the limits of Japan’s 2015 Legislation for Peace and Security. The legislation permits the minimum necessary use of force only when the so-called three new conditions are satisfied, including cases in which an armed attack on a foreign country that is in a close relationship with Japan poses a clear threat to Japan’s survival and to the fundamental rights of its people. It is important to note that, as a matter of law, U.S. participation in a conflict is not itself a requirement for recognizing a situation that threatens Japan’s survival. The Japanese government has also stated with regard to a Taiwan contingency that whether a particular situation constitutes such a threat must be determined comprehensively in light of the specific circumstances actually arising. It is therefore inaccurate to frame the issue as one in which Japan can do nothing unless the United States participates.
However, what is legally possible and what can actually be recognized in practice are different questions. A situation threatening Japan’s survival can be recognized only when there is a clear danger to Japan’s existence and to the rights of its people, and when no other appropriate means are available. Disruption to maritime traffic or higher resource prices alone would not automatically meet that threshold.
Moreover, when Japan seeks to secure safe navigation in a manner that is not directly connected to combat with the opposing state, the framework of a situation threatening Japan’s survival may in some cases be too weighty. In March 2026, views were expressed within the Japanese government that minesweeping in the Strait of Hormuz after a ceasefire could be considered as one option. This is one example of the importance of maritime security measures that are institutionally separated from direct participation in combat.
The same perspective should guide discussion of a Taiwan contingency. The debate should not be reduced to a binary question of whether Japan would exercise the right of collective self-defense. Japan instead needs to strengthen the legal and institutional arrangements that apply before that threshold is reached and in adjacent areas. Specifically, it should clarify the legal basis and timing for measures such as the evacuation of Japanese nationals, maritime security, mine clearance, information sharing, warnings to civilian vessels, coordination with third countries and international organizations, and the alternative use of ports and airports. A U.N. resolution or an international framework led by third countries could be one option. Yet because China is a permanent member of the Security Council and possesses a veto, it would be unrealistic to rely solely on a U.N. resolution. Japan therefore needs multiple legal and diplomatic pathways.
What Should Japan Learn From the Iran War?
The Iran-U.S. war became a major crisis that simultaneously challenged the protection of Japanese nationals and the security of maritime transportation. It demonstrated that preparing for contingencies cannot be reduced to the question of how far the Self-Defense Forces can be used. In the initial phase of a crisis, airport closures and airspace restrictions may halt civilian transportation, while the population requiring evacuation may rapidly expand from the belligerent state to neighboring countries. At sea, Japan may be called upon to help ensure safe navigation even without participating in hostilities, while still facing the risk that such activity could be interpreted as support for one of the parties to the conflict.
The same problems could arise in a Taiwan contingency. The central issue is not to reduce a Taiwan crisis immediately to the questions of a situation threatening Japan’s survival or the exercise of collective self-defense. Rather, Japan needs to institutionalize and operationalize the measures that would become necessary before such a determination: the evacuation of Japanese nationals, the evacuation of residents, the maintenance of air and maritime transportation, protection of sea lanes, and cooperation with third countries. The Iran war has revealed a new “intermediate domain” within the legal and institutional framework Japan has developed with a Taiwan contingency in mind.
Diplomatic efforts to prevent a Taiwan contingency must of course continue. Yet considering what should be done if deterrence fails is also part of security policy. The most important lesson Japan should draw from the Iran War is that the issue should not be framed as a binary choice between participation and non-participation in war. Instead, the many practical tasks that lie between those two poles must be institutionalized in advance.