Questions are emerging in Seoul and Tokyo over whether Washington could eventually ask its key regional allies — South Korea and Japan — to support operations tied to the conflict, particularly given their reliance on energy shipments passing through the Strait of Hormuz and the presence of major U.S. military assets in both countries.
Japan’s Yomiuri Shimbun reported Wednesday that the United States could press Tokyo to provide tangible support when U.S. President Donald Trump meets Japanese Prime Minister Sanae Takaichi later this month.
The discussion reflects a broader concern in the region that a distant war could gradually draw U.S. allies into supporting roles even if they initially seek to remain on the sidelines.
Signs of the conflict’s ripple effects are already visible.
Parts of the U.S. military posture in East Asia appear to be shifting as Washington reallocates resources to the Middle East. U.S. media outlets have reported that the Pentagon is moving elements of a Terminal High Altitude Area Defense (THAAD) system from South Korea to the Middle East. Some Patriot missile batteries stationed with U.S. Forces Korea may also be redeployed.
“If asked whether that would seriously hinder our deterrence strategy against North Korea, I can say with certainty that it would not,” Lee said during a cabinet meeting Tuesday.
Still, the redeployment has sparked debate about the durability of the U.S. security commitment to East Asia at a time when Washington is engaged in a major conflict elsewhere.
Japan hosts roughly 50,000 U.S. troops and provides critical bases for American operations across the Indo-Pacific. At the same time, the Japanese government has been cautious about becoming entangled in the Iran conflict.
Under Japan’s postwar constitutional framework, military participation abroad is tightly constrained. Any direct support for U.S. combat operations would likely require legal justification under Japan’s doctrine of collective self-defense — allowing force to protect an ally if Japan’s own survival is at stake.
Government spokesperson Minoru Kihara recently said the current situation does not constitute an “existential crisis” that would trigger collective self-defense.
Yet pressure could grow if the war disrupts global energy routes. The Strait of Hormuz — through which a large share of Japan’s oil imports passes — remains one of the world’s most vulnerable maritime chokepoints.
If Iran threatens shipping there, Japan could face calls to contribute maritime escorts or logistical support to ensure safe passage for energy supplies.
Despite these concerns, many analysts believe direct military involvement by U.S. allies remains unlikely — for now.
“The possibility of South Korea and Japan becoming involved in the Iran war is rather low,” Matsunaga told AJP.
“The U.S. does not need our military participation in the active war theater in the Middle East, and more importantly it does not want to create vulnerabilities in East Asia that could open a second war front.”
That logic reflects Washington’s broader strategic dilemma: while concentrating forces against Iran, the United States must also deter potential adversaries in Asia, including North Korea and China.
Still, even limited logistical or maritime support could mark a shift in the role U.S. allies play in conflicts beyond their immediate region.
South Korea has long faced concerns about “entrapment” — the risk that alliance commitments could draw it into distant conflicts initiated by Washington.
“If the conflict becomes a prolonged, low-intensity struggle, Iran may rely more on asymmetric tactics and attacks against actors perceived to support the U.S. or Israel,” he said. “But overall, Iran would likely avoid directly targeting third-party countries.”
For both Tokyo and Seoul, the Iran war is quickly becoming a test of alliance politics in an era of globalized security risks.
Neither government appears eager to play an active military role in the conflict. Yet as the war expands and U.S. forces reposition across the globe, the political pressure on allies to contribute — even indirectly — may continue to grow.
For now, both governments hope the conflict remains distant enough to avoid a difficult choice.
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