The Iran War, Changing Battlefields, and the Role of Allies

Bee Yun JO

bjo87@sejong.org​

Research Fellow

Sejong Institute

1. Introduction 

This brief examines the implications of the U.S.-Israeli military operations against Iran by focusing on two linked questions: how the battlefield changed during the war; and what the war reveals about the role the United States expects from allies in times of contingency. It takes as its point of departure the Trump administration’s 2026 National Defense Strategy, which identifies Israel as a “model ally” that has demonstrated both the will and the capability to defend itself with “critical but limited” U.S. support. The brief uses the Iran war to test the meaning and limits of that concept in actual wartime conditions. It also asks what lessons, if any, should be drawn for South Korea and the Korean Peninsula.

The central finding is that the war illuminates both the appeal and the limitations of the “model ally” framework. On the one hand, the opening phase of the war did reflect important features of the model: Israel assumed a large share of the offensive burden, demonstrated initiative and operational capability, and worked in close coordination with the United States, while Washington provided decisive support in critical areas. On the other hand, once the conflict expanded geographically, the burdens on the United States increased rather than decreased. Missile defense, sea-lane protection, energy security, escalation control, and the defense of regional partners all became larger U.S. responsibilities. The war therefore suggests that a capable and willing ally does not necessarily reduce the strategic burden on the United States. In some cases, an ally that performs strongly at the tactical or operational level may still generate wider strategic liabilities for Washington as the conflict broadens.

A second major conclusion is that the war demonstrates a broader transformation in the character of modern warfare. The conflict did not remain a narrowly defined air campaign against targets on Iranian territory. Instead, it evolved into a multi-domain battlespace in which asymmetric attrition, intelligence superiority, maritime insecurity, energy vulnerability, and nuclear-related risks became deeply intertwined. The war moved through several major phases: the initial U.S.-Israeli strike aimed at decapitation, disruption of command-and-control, degradation of nuclear and missile capabilities, and rapid establishment of air superiority; Iran’s retaliatory drone and missile attacks combined with the tightening of control over the Strait of Hormuz; the broadening of the war into organized cost-imposition against Gulf energy and infrastructure targets; the growing importance of Kharg Island and nearby maritime positions as strategic nodes; and finally, a phase in which rising escalation risks coexisted with ceasefire proposals and coercive diplomacy. By early April, the war had become not simply a war over Iranian territory, but a wider conflict stretching across the Gulf, the Strait of Hormuz, the Red Sea, and nearby islands.

2. The Iran War and Battlefield (Future of Warfare)

One of the clearest features of this new battlefield was the deepening of asymmetric attrition. Iran relied heavily on cheap, numerous systems such as Shahed-series drones, as well as cruise and ballistic missiles, to impose cumulative costs on Israeli, American, and allied air defenses. The significance of this was not merely military but economic and strategic. Relatively inexpensive offensive systems forced the defenders to expend far more costly interceptors and defensive assets, thereby revealing a widening cost imbalance between mass attack and high-end defense. In this respect, the war underscored that battlefield effectiveness can no longer be measured only in terms of precision or lethality. The ability to impose exhaustion, drain inventories, and manipulate the attacker-defender cost ratio has become a central strategic variable in its own right.

A second defining feature of the war was the decisive role of intelligence, surveillance, and target identification. The opening phase of the campaign depended on extremely accurate information regarding the movement of Iranian leaders, key meetings, command structures, and nuclear- or missile-related targets. The brief emphasizes that what made early decapitation attempts and the rapid seizure of the operational initiative possible was not only advanced weaponry, but superior knowledge of timing, location, and target vulnerability. In this sense, the war demonstrated that in contemporary conflict, intelligence advantage is not simply an enabling condition but one of the primary determinants of whether a state can shape the first phase of war on favorable terms.

A third major transformation lay in the elevation of energy security and maritime access from background conditions to central components of the battlefield itself. Iran’s effort to tighten control over the Strait of Hormuz, selectively allow certain shipping to pass, and threaten Gulf energy, electricity, desalination, and IT infrastructure showed that infrastructure and chokepoints can serve as instruments of coercion alongside more conventional military action. The rise of Kharg Island as a strategic node and the apparent U.S. preparation for limited amphibious or ground action to secure maritime access further reinforced this point. Energy systems, sea-lanes, and infrastructure resilience were not peripheral concerns. They became part of the war’s operational core. Future conflict, the brief suggests, is likely to be shaped not only by who controls the air or the land, but also by who can endure or weaponize disruptions to energy, logistics, and commercial flows.

The war also reopened the debate on nuclear threshold. Although nuclear facilities and nuclear programs featured prominently in the war’s rhetoric and targeting logic, the immediate risk was less direct nuclear use than nuclear-related instability. Strikes near nuclear facilities generated alarm over nuclear safety and the possibility of regional disaster, even as actual nuclear escalation remained constrained. There is therefore a paradoxical situation: nuclear politics became more salient, nuclear-related fear intensified, and nuclear sites became more central to coercive signaling, yet the threshold for actual nuclear weapon use remained high. That should not be mistaken for stability. Rather, it indicates that nuclear infrastructure itself may become increasingly vulnerable to coercion, hostage-taking, or escalatory pressure in conventional war.

3. Implications on the Role of Alliances

Against this background, the brief draws implications on the role of allies. It finds that U.S.-Israeli cooperation at the opening stage of the war came close to the idealized burden-sharing logic set out in the 2026 National Defense Strategy. Israel contributed long-developed intelligence, target identification, and offensive initiative. The United States supported maritime and southern axes, air and missile defense, command-and-control, and strategic targeting. In that initial moment, the division of labor appeared to validate the idea of an ally that assumes primary responsibility while receiving decisive but selective U.S. backing. Yet this same case also exposed the fragility of the concept. Once Iran’s retaliation widened the battlespace into the Gulf and turned maritime access and energy security into strategic concerns, the United States was pulled into a broader set of missions not reducible to support for Israel alone. Protecting sea-lanes, stabilizing the energy market, defending Gulf partners, and managing escalation became unmistakably American burdens. The result was not a clean reduction in U.S. exposure, but a more complicated sharing of risk in which American obligations expanded as the war widened.

The Iran war also reveals that the United States does not expect a single, uniform role from all allies and partners. Rather, wartime expectations are differentiated according to alliance type, geography, political constraints, and military capability. Gulf states, for example, were not treated as a single bloc. Bahrain, Qatar, and Kuwait, where U.S. bases and forces are concentrated, were most important as operational hubs, logistics centers, and command nodes. Bahrain, Qatar, the UAE, and Oman acquired additional significance because of their direct exposure to the Strait of Hormuz and the Gulf, making maritime security, freedom of navigation, air defense, and energy stability central to their wartime relevance. Saudi Arabia and the UAE, although not formal treaty allies in the same sense as some others, mattered because of their military capacity, energy importance, financial weight, and ability to grant access and cooperation. This differentiated pattern reveals that the United States operates through a layered partner structure rather than through a single model of alliance solidarity.

A similar logic applies to NATO and Indo-Pacific allies. European allies were not positioned to participate as direct co-belligerents in the same way Israel did. Geographic distance, legal constraints, and the limits of NATO’s collective defense framework in a Middle Eastern contingency made direct military participation difficult. Their more realistic contribution lay in diplomatic and normative support, maritime security cooperation, and efforts to stabilize energy markets and commercial flows. Indo-Pacific allies were also subject to more constrained expectations. Japan, because of domestic legal restrictions and the continuing salience of its own theater, was relevant mainly in terms of limited maritime-security support, economic-security interests tied to Hormuz, and crisis-management roles after de-escalation. South Korea’s strategic importance lay in the stable operation of U.S. Forces Korea, the maintenance of deterrence on the Peninsula, support for the strategic flexibility of U.S. forces, and continued alliance coordination in a period when American attention and assets might be pulled toward the Middle East. The broader implication is that even among treaty allies, the United States does not assign identical roles. It distributes functions according to theater position, exposure to direct threat, domestic political constraints, and preexisting security burdens.

The manuscript’s most important policy discussion concerns the implications for South Korea and the Korean Peninsula. It warns strongly against any mechanical application of the Iran case to Korea. North Korea is not Iran, and South Korea is not Israel. North Korea already possesses operational nuclear weapons and delivery systems. It sits adjacent to Seoul and the greater metropolitan area, with the capacity to inflict immediate and massive damage through artillery, missiles, drones, and special operations forces. South Korea, moreover, operates under different domestic political conditions from Israel and cannot assume the same degree of bipartisan consensus on preventive war. For those reasons, the lessons from the Iran war must be filtered through the far harsher escalation geometry, denser alliance entanglement, and greater political sensitivity of the Korean theater.

Even so, the Iran war does raise some questions for Korea. It suggests that, at least in theory, the United States could contemplate preventive or preemptive action against a regional adversary under certain conditions. It also raises the question of what would be expected of South Korea if Washington pursued such a course, and what the implications would be if Seoul did not want such a war. A further question concerns the demands of participating in what is effectively “America’s war” in another theater, including a Taiwan contingency.

If model ally is reframed to the situation of South Korea, model ally is not simply the ability to join offensive action in the Israeli manner. It is the ability to sustain deterrence, absorb and suppress the early phase of attack, preserve political cohesion, and keep the alliance operational under severe stress. That implies several practical requirements. First, South Korea must strengthen high-confidence ISR and human intelligence capabilities directed at North Korea’s leadership, command networks, artillery, missile systems, drones, and critical facilities. Second, it must enhance war-sustainment capacity, including interceptor inventories, logistical endurance, maintenance, stockpiles, and broader industrial preparedness for prolonged conflict. Third, it must improve its ability to manage the early phase of war on the Peninsula in a way that reduces pressure for rapid escalation while preserving room for alliance coordination. Fourth, it must maintain political sustainability at home, because military effectiveness without domestic legitimacy would be brittle in any prolonged crisis.

4. Policy Recommendations

The policy recommendations follow directly from this analysis. South Korea should visibly demonstrate a stronger capacity for primary responsibility on the Peninsula. It should invest in the intelligence and resilience needed for a much harsher and more immediate threat environment. It should deepen long-war preparedness, not only in terms of combat power but also in logistics, sustainment, industrial output, and the political ability to endure protracted confrontation. It should also preserve mechanisms of strategic consultation and political control within the alliance so that neither side is pulled into wider wars involuntarily. At the same time, South Korea should recognize that future alliance contributions will increasingly be judged not only by willingness to fight, but by the ability to sustain deterrence, support allied operations, and contribute to wider strategic resilience in theater-specific ways.

In sum, the brief presents the Iran war as a revealing case of contemporary alliance politics and changing warfare. It shows that modern war is increasingly defined by asymmetric attrition, intelligence advantage, energy and maritime vulnerability, and nuclear-related instability. It shows that the U.S. concept of a “model ally” can work at the opening stage of war but does not necessarily lighten America’s burdens as the conflict expands. And it shows that wartime expectations are distributed differentially across allies and partners rather than according to a single template. For South Korea, the central lesson is neither to become another Israel nor to dismiss the case as irrelevant. It is to define a distinctly Korean version of alliance responsibility rooted in deterrence, resilience, war-sustainment, and strategic coordination under conditions far more dangerous than those of the Iran case.

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