Before the first missile struck Iran, Japan had already begun preparing. For years, Tokyo had been building a network of economic partnerships across Southeast Asia, spanning semiconductor supply chains, critical minerals, and investment diversification. The effort never sounded like a military alliance because it was not one.
Then war broke out.
When U.S. and Israeli military operations against Iran began in February 2026 and the Strait of Hormuz was effectively shut down from early March, nearly 93 percent of Japan's oil imports were suddenly at risk, making the situation feel far more urgent.
One Strait, One Major Question
The Strait of Hormuz is the only maritime route through which oil, natural gas, and other cargo can exit the Persian Gulf. According to data from the U.S. Energy Information Administration (EIA), oil flows through the Strait averaged 20.1 million barrels per day in the first quarter of 2025, equivalent to roughly one-fifth of global oil consumption.
Asia was the region most exposed to the disruption. Nearly every Asian country depends heavily on Middle Eastern oil, and when the conflict erupted, the region experienced a genuine energy shock. Governments scrambled for solutions, with few short-term options available. Japan was no exception.
On March 16, the Japanese government began releasing 80 million barrels from its strategic petroleum reserves, equivalent to approximately 45 days of domestic demand, in an effort to calm markets and minimize economic disruption.
But releasing reserves was only an emergency measure. What Tokyo recognized was a deeper problem: energy dependence could not be solved through stockpiles alone.
From Chequebook Diplomacy to Strategic Architecture
Japan's most concrete response came on April 15, 2026. Prime Minister Sanae Takaichi announced the launch of the Partnership on Wide Energy and Resources Resilience Asia (POWERR Asia), an energy cooperation framework aimed directly at Southeast Asia, which has become a critical backbone of Japan's supply chains.
The initiative's USD 10 billion allocation is roughly equivalent to the value of one year's crude oil imports for all ASEAN countries combined. The framework operates on two levels: emergency response and long-term structural resilience.
In the short term, POWERR Asia finances crude oil procurement and helps maintain energy supply chains across Asian economies. In the long term, it supports the development of shared petroleum reserve systems and the diversification of energy sources.
At first glance, the initiative appears to be designed to assist the region. In reality, Japan is also protecting itself.
When energy supplies in countries such as Viet Nam, Thailand, or Malaysia are disrupted, factories producing components for Japan's automotive and electronics industries are disrupted as well. Safeguarding Southeast Asia's energy security, therefore, is also a way of safeguarding Japan's own industrial resilience.
Before the War: Supply Chains Had Already Begun Shifting
The Iran conflict merely accelerated a process that had already been underway for years.
Data from the Japanese research institution RIETI covering the period from 2009 to 2022 show that Japanese multinational corporations responded to rising geopolitical risks by diversifying production from China to ASEAN economies, rather than fully decoupling from China or reshoring operations back to Japan.
The pressure is even more evident in the critical minerals sector. The growing importance of minerals such as lithium, cobalt, and rare earth elements has made supply chain resilience a central issue in both international relations and national economic policy.
Yet Japan had begun addressing this challenge long before the current crisis. For more than 15 years, the Japan Organization for Metals and Energy Security (JOGMEC) has systematically treated mineral supply chains as strategic infrastructure, pursuing diversification across multiple nodes of the supply chain and a wide range of operations around the world.
In October 2025, Japan and the United States signed a framework agreement to strengthen cooperation on critical minerals and rare earths. As part of the initiative, JOGMEC also signed a memorandum of understanding with the U.S. company REAlloys Inc. to jointly develop mineral processing technologies.
The foundations of economic integration were already in place as well. Total ASEAN–Japan two-way trade reached USD 236.4 billion in 2024, while Japanese foreign direct investment flows into ASEAN amounted to USD 17.5 billion.
Not a Military Alliance, but Not Just Business
Prime Minister Takaichi's visit to Viet Nam from May 1 to 3, 2026, reflected a tone that differed from a conventional diplomatic tour.
The two countries agreed to increase Japanese investment in Viet Nam to USD 5 billion annually and to expand bilateral trade to USD 60 billion by 2030, with particular emphasis on energy security, critical minerals, and supply chain resilience.
ASEAN itself has also begun responding more seriously. Philippine President Ferdinand Marcos Jr. called for stronger regional coordination and urged ASEAN to activate the ASEAN Petroleum Security Agreement (APSA), a fuel-sharing mechanism designed to respond to supply disruptions. He also proposed joint emergency exercises and a review of regional petroleum reserve arrangements.
The energy crisis triggered by conflict in the Middle East exposed significant vulnerabilities in the region's economic and energy resilience. It demonstrated that security cannot be reduced solely to defense cooperation.
For both Japan and Southeast Asia, safeguarding energy flows, critical resources, and supply chains has become just as important as traditional military security. In that sense, the emerging architecture is not a military alliance, but it is no longer merely a business relationship either.
