The Hormuz Strait Crisis and Japan's Security: The Reality of "Maritime Traffic Line Defense" Presented by the Urgent Situation in Iran

On April 20, 2026, reports emerged of a U.S. military attack on Iranian vessels, significantly escalating tensions in the Middle East. Amidst concerns about potential retaliation from the Iranian military, the second round of talks between the U.S. and Iran remains uncertain. This situation poses a serious challenge to Japan, which imports about one-fifth of its crude oil from the Middle East and relies heavily on the Strait of Hormuz for its energy supply.

The Strait of Hormuz is the world's most critical maritime chokepoint, through which approximately 20 million barrels of crude oil pass daily. About 95% of Japan's crude oil imports depend on the Middle East, with the majority transiting through this strait. On April 18, the Iranian Foreign Minister stated that Iran is prepared to "open the strait to commercial vessels" under certain conditions; however, the Iranian President clearly rejected any concessions regarding nuclear development on April 19. There is a noticeable divide between hardliners and moderates within Iran, and the situation remains precarious.

The rising tensions are immediately impacting the energy market. New York crude oil futures have already surged to around $91 per barrel, raising concerns about a direct blow to the Japanese economy. Japan maintains a relatively high level of oil reserves globally, reportedly securing about 200 days' worth of supply. However, if a long-term closure of the strait or navigation restrictions occur, the depletion of reserves would inevitably affect the lives of citizens and industrial activities. Increases in electricity rates, gasoline prices, and logistics costs will certainly push consumer prices higher, complicating the Bank of Japan's monetary policy management.

Japan's Ministry of Defense and Self-Defense Forces have been addressing the long-term challenge of ensuring the safety of maritime shipping routes. Following the tanker attack near the Strait of Hormuz in 2019, Japan has promoted its own maritime security initiative and has been conducting information-gathering activities in the Middle Eastern waters through the Japan Maritime Self-Defense Force. Currently, escort ships and P-3C patrol aircraft are deployed to continue monitoring the maritime situation. However, the Self-Defense Forces' escort activities under actual combat conditions remain limited due to legal constraints regarding the exercise of collective self-defense and the use of weapons, making cooperation within the framework of the Japan-U.S. alliance essential for comprehensive maritime route defense.

At the same time, a fundamental review of the national security system is underway domestically. A bill to establish a "National Intelligence Agency" is currently being discussed in the House of Representatives, with negotiations on the voting schedule between the ruling and opposition parties. This bill represents an important step toward the creation of a Japanese version of a unified intelligence agency. It aims to centralize the information collection and analysis functions that have been dispersed among the National Police Agency, Public Security Intelligence Agency, Defense Intelligence Headquarters, and the Ministry of Foreign Affairs' International Information Coordination Organization, significantly enhancing the quality and quantity of strategic information. As the situation in the Middle East rapidly changes and the security environment in East Asia deteriorates simultaneously, there is an increasing demand for rapid decision-making based on accurate information.

The establishment of the National Intelligence Agency is not merely about institutional integration. It is expected to enhance various capabilities, including strengthening human intelligence (HUMINT), expanding information collection systems in cyberspace, and deepening information sharing with allied nations. In particular, building a human intelligence network in the Middle East and Africa has long been considered a weakness in Japan's information-gathering capabilities, and the current Iranian crisis has highlighted its importance once again.

From the perspective of the Japan-U.S. alliance, military actions by the U.S. against Iran under the Trump administration could also impact the operations of U.S. forces stationed in Japan. If the carrier strike group of the 7th Fleet, based in Yokosuka, or some of the air power at Kadena Air Base were diverted to the Middle East, there are concerns that this could lead to a decrease in deterrence in the East China Sea and South China Sea. China is closely monitoring these movements of U.S. military forces and may seek to exploit any "gaps" that arise in the East Asian security environment.

In fact, the movements of the Chinese Navy warrant caution. The People's Liberation Army Navy has currently deployed several improved versions of the 093B class, a second-generation nuclear submarine, and is also observed to be advancing the construction of the next-generation 096 class strategic missile submarines. The continued militarization of bases in the South China Sea, the normalization of military pressure around Taiwan, and the strengthening of cooperative activities between the Coast Guard and Navy in the East China Sea are all contributing to an expanding Chinese presence in Japan's surrounding waters. The period when U.S. attention is directed toward the Middle East carries the risk of accelerating such movements in Northeast Asia.

The situation on the Korean Peninsula also requires close attention. On April 20, Ukrainian President Zelensky expressed concerns about the potential lifting of U.S. sanctions against Russia, which is also an important message for North Korea. If the perception that easing or revising sanctions "works in favor of nuclear-armed states" takes hold in Pyongyang, the motivation for denuclearization negotiations could weaken further, potentially leading to a continuation and acceleration of nuclear and missile development. For Japan, the threat of North Korean ballistic missiles is a reality, and maintaining and strengthening the ballistic missile defense system through the Aegis system is one of the top priorities.

The crisis in the Strait of Hormuz vividly illustrates the complex nature of the security challenges Japan faces. Energy security, maritime route defense, the operation of the Japan-U.S. alliance, the enhancement of information capabilities, and the maintenance of deterrence in surrounding waters—these are not isolated issues but must be understood as interconnected as a whole. The establishment of the National Intelligence Agency should be positioned as a foundation for constructing a comprehensive security strategy that encompasses this entire picture.

Japan now stands between two potential flashpoints: the Middle East and East Asia. If one flashpoint explodes, the other is likely to smolder. To prevent such a chain reaction, close cooperation with allies, strengthening independent information collection and analysis capabilities, and above all, calm and transparent communication of information to the public are essential. The security environment in the spring of 2026 signals that the boundary between "peacetime" and "crisis" is becoming increasingly blurred for Japan.