The Security Vacuum Risk of the Final U.S. Withdrawal from Iraq Amid the Iran-U.S. War

Executive Summary

The withdrawal of U.S. forces from Iraq, to be completed by September 30, is a scheduled procedure under a 2024 Baghdad-Washington agreement. However, its timing—coinciding with the sixth month of the ongoing Iran-U.S. war—raises concerns that the resulting vacuum in air defense and detection assets in the Kurdistan region could remove a defensive layer along the transit routes for Iranian missiles and drones. Although the Iraqi government is acquiring new air defense systems, a deployment lag is unavoidable. The baseline scenario for the next three to six months is therefore the persistence of low-intensity risks (50% probability). South Korean companies must immediately reassess the exposure of their operations in Iraq and neighboring countries (Jordan, the UAE, Saudi Arabia) to this air defense gap and maintain active systems for diversifying crude oil procurement and monitoring secondary sanctions. The core challenge is to avoid betting on a single outcome and instead prepare a dual-track response plan that can be activated immediately upon a trigger event.

I. Situational Analysis

The Final Withdrawal from Iraq: A Situational Analysis

1. Background and Developments

The September 30 withdrawal of U.S. forces from Iraq is a scheduled event based on a 2024 agreement between Baghdad and Washington [2][10]. The core of this agreement was to transition the mission of the U.S.-led coalition from a combat and advisory role to a bilateral security cooperation framework [1]. Operation Inherent Resolve, the mission to defeat IS, has provided the legal and military justification for the U.S. presence in Iraq for over a decade since the group's rise in 2014. This withdrawal concludes a major chapter of the U.S. military presence in Iraq, which has been continuous since the fall of Saddam Hussein's regime in 2003 [2].

The withdrawal schedule itself had been finalized separately from the Iran-U.S. war. However, its implementation coincides with the sixth and seventh months of the war with Iran, which began on February 28, lending new significance to the U.S. military vacuum in Iraq [6][9]. Iraq borders Iran, and Shia militias (Hashd al-Shaabi) exert considerable political and military influence there. The Kurdistan region, where the U.S.-led coalition's air defense and detection assets have been concentrated, has also served as a repeated transit route for Iranian missiles and drones targeting Israel or U.S. bases in the Gulf [1]. Kurdistan's Interior Minister, Rebar Ahmed, stated to the media, "According to the existing agreement, these forces must withdraw by the end of September, and in fact, they have already begun the withdrawal" [10].

2. Current Situation

The UAE-based media outlet The National reports that Iraq's neighbors are recalibrating their security calculations following the withdrawal of coalition air defense systems [1]. It notes that the vacuum left by U.S. detection and interception assets in Kurdistan effectively removes a defensive layer along the transit routes for Iranian missiles and drones [1]. This view suggests the problem extends beyond Iraq, potentially creating a cascading effect on the broader air defense networks of regional states like Jordan, Saudi Arabia, and the UAE.

In a follow-up report, the same media outlet noted that Iraq plans to acquire new air defense systems as the coalition mission concludes [7]. An Iraqi government official stated, "Operation Inherent Resolve will end in Iraq on September 30," but added that "the operation itself may continue, as IS exists in other countries," without specifying which ones [7]. This comment can be interpreted as the Iraqi government acknowledging the remaining threat from IS while signaling its intention to fill the security gap with its own air defense capabilities following the U.S. withdrawal.

The Dutch-language media outlet Starnieuws framed the withdrawal as a choice between "sovereignty or battlefield" [4]. This illustrates the dual perspectives within Iraq itself, where the move is seen by some as a restoration of sovereignty and by others as a deepening of vulnerability due to the ensuing security vacuum.

Meanwhile, the Iran-U.S. war itself has not entered an endgame. At its outset six months ago on February 28, President Trump predicted the conflict would last "four to five weeks," but this did not come to pass, and his subsequent predictions of an early conclusion have consistently been incorrect [5][12]. President Trump recently claimed the war would end immediately after the November 3 midterm elections [14][15], a statement that fits a narrative framing Iran as escalating provocations to influence the electoral outcome. Compounding this is a Wall Street Journal report that Secretary of Defense Hegseth is quietly considering extending troop deployments until 2027 [12]. This creates a contradictory situation where, separate from the Iraq withdrawal, the prospect of a long-term U.S. military presence in the wider region is paradoxically growing.

3. Key Actors and Positions

Iraqi Government (Baghdad)Based on the 2024 agreement, Baghdad intends to proceed with the withdrawal as scheduled while seeking to minimize the security vacuum by acquiring new air defense systems [7]. While officially acknowledging the residual threat from IS, it treats the end of Operation Inherent Resolve within Iraq as a fait accompli.

Kurdistan Regional GovernmentThe KRG is serving to officially confirm the implementation of the withdrawal. Interior Minister Ahmed's statement indicates that the withdrawal is already underway [10]. As the region where coalition air defense assets have been concentrated, Kurdistan is the actor that will most directly experience the security vacuum resulting from the withdrawal.

The United States (Washington)Washington presents the Iraq withdrawal as a symbolic measure closing a chapter of military intervention that began in 2003 [2]. At the same time, it displays a dual approach by extending troop deployments in other parts of the region amid the protracted war with Iran [12]. This suggests the withdrawal from Iraq is not a signal of a broader disengagement from the Middle East but rather a realignment toward a different form of military presence with a different mission.

IranLeveraging its influence over Shia militias in Iraq, Iran has an incentive to use the U.S. military vacuum as an opportunity to expand its regional influence. Concurrently, it is engaged in low-intensity conflict with the United States by asserting control over passage through the Strait of Hormuz [6][9], raising the possibility that the vacuum in Iraq could become another tool for Iran to pressure the U.S.

Gulf Buffer States (e.g., UAE, Jordan)These states are concerned about the ripple effects that the air defense vacuum in Iraq could have on the entire regional air defense network [1]. Having already been targets of Iranian retaliatory strikes [6], they view the withdrawal of U.S. assets from Iraq as an issue directly linked to their own national security.

4. Key Issues

The central issue of this withdrawal is the juxtaposition of a definite schedule with indefinite security implications. The September 30 date is fixed by the 2024 agreement and is unlikely to be altered [2][10]. However, the timing complicates the withdrawal's true meaning, as it coincides with the seventh month of the Iran-U.S. war, a period characterized by recurring cycles of escalation and de-escalation [9][15].

The first issue is the actual scale of the air defense vacuum. The National posits that the withdrawal of detection and interception assets from the Kurdistan region will lead to the loss of a defensive layer along Iranian missile and drone routes [1]. It remains uncertain to what extent the Iraqi government's plan to acquire new systems can fill this gap [7].

The second issue is distinguishing between "withdrawal" and "realignment." The withdrawal from Iraq signifies the end of Operation Inherent Resolve within that country, but the possibility remains that the operation itself could continue elsewhere [7]. At the same time, an extension of U.S. troop deployments related to the Iran war is being considered until 2027 [12], making it difficult to simplify the Iraq withdrawal as a U.S. departure from the Middle East.

The third issue is how Iran will respond. Iran is simultaneously pursuing two tracks: expanding its influence through militias in Iraq and applying pressure on the U.S. via the Strait of Hormuz [6][9]. Which of these two tracks will benefit more from the U.S. military vacuum in Iraq will likely be a key variable in determining the future direction of the regional security architecture.

II. In-Depth Analysis

The Final Withdrawal from Iraq: An In-Depth Analysis

1. Analysis of Root Causes

The ostensible reason for this withdrawal is the completion of the military mission to defeat IS [2][7]. The actual driver, however, was the political demands of the Baghdad government in 2024. Pro-Iranian Shia parties within the Iraqi government had consistently pressured for a withdrawal schedule, framing the U.S. military presence as a violation of sovereignty. Washington accommodated this pressure by opting for a compromise: reshaping the relationship into a "bilateral security cooperation" framework rather than making a clean break [1]. Thus, the withdrawal is a product of Iraqi domestic politics, not a decision stemming from an assessment of an improved regional security environment.

The problem is that the regional security environment changed fundamentally between when the withdrawal schedule was finalized in 2024 and its implementation in September 2026. When the agreement was made in 2024, the Israel-Hamas war was underway, but a direct military conflict between the U.S. and Iran was not widely anticipated. The situation was completely altered after the U.S. and Israeli airstrikes on Iran on February 28 [3][8]. The Iranian regime did not collapse following Khamenei's death, and after the Islamabad Memorandum expired in July, Iran shifted to the offensive, using force to control passage through the Strait of Hormuz [6][9]. The Iraq withdrawal is therefore the result of a collision between the planned logic of ending the anti-IS mission and the contingent reality of an ongoing war with Iran. There is no evidence that Washington considered adjusting the timeline; the inertia of adhering to the agreement seems to have taken precedence over a reassessment of the security situation.

2. Structural Context

Iraq is a point of direct contact between the spheres of influence of two major powers: the United States and Iran. Politically, pro-Iranian Shia militias like Hashd al-Shaabi have extensively infiltrated the Iraqi regular army and government organizations. This means that Iran's influence will not automatically diminish with the physical withdrawal of U.S. forces. On the contrary, the removal of the U.S. as a counterweight is likely to strengthen the relative position of pro-Iranian factions.

In terms of the security architecture, the air defense and detection assets in the Kurdistan region were not solely for Iraq's benefit. The area has been a recurring transit route for Iranian missiles and drones targeting Israel or U.S. bases in the Gulf [1]. In effect, the coalition's air defense network in Iraq was one pillar of a wider regional defense system that extended to Jordan, Saudi Arabia, and the UAE. With this pillar removed, neighboring countries face the burden of filling the gap with their own air defense budgets and assets. The report in The National that "neighboring countries are recalibrating their security calculations" points to this structural chain reaction [1].

Economically, the U.S. withdrawal raises the possibility of a deterrence vacuum against remaining IS forces. The admission by an Iraqi official that "the operation itself may continue, as IS exists in other countries" [7] signifies that the government itself acknowledges the IS threat within Iraq has not been fully eliminated. The failure to name specific countries, however, can be interpreted as a political calculation by the Iraqi government to downplay the scale of the residual threat within its own borders.

A broader structural context is that the U.S. war with Iran is solidifying into a war of attrition. The report that U.S. Secretary of Defense Hegseth is quietly extending troop deployments until 2027 [12] suggests Washington has limited capacity to redeploy forces within the region. With inventories of THAAD and Patriot interceptors down by at least 38% and up to 65%, respectively [6], it is plausible that the forces and assets freed up by the Iraq withdrawal could be reassigned to other fronts, particularly for responding to a direct conflict with Iran. Ultimately, the withdrawal from Iraq should be seen as one piece of a broader regional force realignment.

3. Historical Precedents and Comparative Cases

The Obama administration's 2011 withdrawal from Iraq is the most direct point of comparison. At that time, U.S. forces also conducted a full withdrawal after failing to renew the Status of Forces Agreement (SOFA) with the Iraqi government. The result, three years later, was the rapid expansion of IS. The Iraqi army effectively surrendered major cities, including Mosul, to IS, forcing the United States to redeploy troops in 2014. Given that the Iraqi government itself does not deny the residual threat from IS [7], one cannot be entirely optimistic that the current withdrawal will not follow a similar path.

However, there is a crucial difference between 2011 and 2026. The 2011 withdrawal occurred when U.S.-Iran relations were relatively stable, whereas the current one is taking place while the two countries are in direct conflict. This means the withdrawal is not merely the end of the anti-IS operation but has the appearance of a U.S. retreat from one front in an ongoing war with Iran. This creates a structurally more dangerous combination than in 2011, as it expands Iran's opportunities to use Iraq as a lever of pressure against the United States.

A comparison with the 2021 withdrawal from Afghanistan also offers insights. In that case, the U.S. pushed ahead with the withdrawal to meet a political deadline, and an overestimation of the local government forces' self-defense capabilities led to the fall of Kabul. In the current Iraq withdrawal, the Iraqi government's rush to acquire new air defense systems [7] is evidence that it recognizes its own capability gaps. However, unlike the Afghan army, the Iraqi military has at least a decade of experience conducting counter-IS operations alongside U.S. forces and also has battle-hardened Shia militias at its disposal, making a complete collapse scenario different in nature. The problem is less a risk of collapse and more the possibility that the security vacuum will be filled by forces under Iranian influence.

4. Key Variables Shaping Future Developments

The first variable is the future trajectory of the U.S.-Iran war. President Trump has stated the war will end immediately after the November 3 midterm elections [14][15], but the credibility of this claim is low, as it is one of many repeated optimistic forecasts [5][12]. Iran, for its part, is pursuing a strategy of increasing pressure ahead of the election [15], so the possibility that the Iraq withdrawal could coincide with an intensification of the war cannot be ruled out.

The second variable is the speed and effectiveness of the Iraqi government's acquisition of a new air defense system. The key question is whether the new system mentioned by the government [7] can effectively replace the detection and interception capabilities of the former coalition assets. If its deployment is delayed or its performance falls short of the previous system, the air defense burden on neighboring countries along the transit routes of Iranian missiles and drones will increase proportionally [1].

The third variable is the political maneuvering of pro-Iranian Shia militias such as Hashd al-Shaabi. The speed at which these groups expand their position within the Iraqi government after the removal of the U.S. as a counterweight will determine how quickly Iraq is transformed into a base for Iranian operations against the U.S. and Israel.

The fourth variable is the direction of Washington's strategic realignment in the region after the U.S. midterm elections. Considering both the report that troop deployments are being extended to 2027 [12] and the observation of a growing gap between the stated priority of the Indo-Pacific and actual U.S. intervention in the Middle East [11], it will likely become clear in the coming months whether the assets withdrawn from Iraq will be absorbed by other fronts or will be part of a broader regional drawdown.