Iran war exposes the limits of US military power

Editor's note: Xu Weijun is an assistant research professor at the Institute of Public Policy, South China University of Technology. His research interests include East Asian international relations, nationalism, Chinese diplomacy, and China-U.S. relations. The article reflects the author's opinions and not necessarily those of CGTN.

Since the United States and Israel launched high-intensity strikes against Iran on February 28, the key variable shaping the battlefield has gradually shifted. The critical factor has shifted from the tactical accuracy and destructive impact of a single strike to whether the US is capable of sustaining the rapid consumption of precision-guided munitions and air and missile defense interceptors during a prolonged, high-intensity confrontation.

Media reports indicate that the White House is planning to convene executives from major defense contractors and urge them to accelerate production, while the Pentagon is also preparing a supplemental budget of approximately $50 billion to address stockpile shortfalls caused by recent operations. These developments suggest that the capacity of the US defense industry, especially its ability to produce munitions and replenish inventories, has already become a major factor constraining further military operations against Iran.

Real-world constraints on US military strikes against Iran

Meanwhile, domestic political skepticism over military action against Iran has intensified in the US. The tug-of-war in Congress concerning the president's war powers has escalated. Despite the Senate's rejection of a resolution that would have restricted President Trump's authority to use force against Iran, the discord between the two parties over war authorization has escalated significantly. 

Moreover, a Reuters/Ipsos poll shows that only 27% of Americans support military strikes on Iran, reflecting strong public resistance to grinding conflicts. This suggests that the Trump administration's domestic political legitimacy and popular support for sustaining large-scale, long-duration military operations against Iran are relatively weak. In this context, the high cost of a protracted war may reshape the Trump administration's willingness and strategic choices, pushing it toward ending the current campaign with a "narrative victory" rather than continuing to pursue difficult long-term objectives.

While the US has the capacity to address the funding needs for operations against Iran in the short term by enacting a supplemental appropriations bill, the stockpiles and production capacity of relevant weaponry may constrain further military actions. Beyond deploying considerable naval and air assets to the Middle East, the US has also expended large quantities of precision-guided munitions and advanced air defense and anti-missile interceptors during this campaign, including Tomahawk cruise missiles, Patriot missiles, Standard Missile-3 missiles, THAAD interceptors, and LUCAS drones. According to The Washington Post, the US is depleting its stocks of precision weapons and sophisticated air defense missiles at a striking pace, which could force the US military to "prioritize which targets to intercept" within days.

These key weapons share several characteristics: high production costs, slow manufacturing rates, and lengthy replenishment cycles for stockpiles. Given the current conflict's ammunition expenditure far exceeding expectations, the defense industry's production capacity will soon become a strategic constraint limiting the sustainability of US military operations against Iran. 

It is true that, relying on its globally leading military capabilities and vast strategic reserves, the US could, if determined to pursue a long and high-intensity campaign against Iran, sustain battlefield consumption in the short term by reallocating munitions from stockpiles positioned across different theaters. However, this "robbing Peter to pay Paul" approach to inventory allocation would directly erode the US military's strategic reserves for higher-intensity scenarios, resulting in irreversible strategic depletion of its global military posture.

From the perspective of attacking, as the US and Israel rapidly secure air superiority over Iranian airspace and suppress Iran's air-defense capabilities, US forces can reduce its reliance on high-cost precision strike munitions such as Tomahawk cruise missiles. Instead, it can sustain strikes against Iran through the large-scale use of guided bombs such as the Joint Direct Attack Munition (JDAM), which exist in larger stockpiles, can be replenished through mass production more quickly, and have a lower unit cost. This would significantly reduce the cost of operations against Iran and materially improve the sustainability of the campaign.

However, from the perspective of defending, intercepting Iranian retaliations will entail continued and large-scale depletion of interceptor munitions. The long-term trajectory of this conflict will largely depend on the competition between the two sides with regard to stockpile size, the defense industry's capacity for mass production, and supply-chain resilience. Should US strikes achieve decisive progress in destroying Iran's missile launch platforms, its missile and drone stockpiles, and its core military production capabilities, this would fundamentally weaken Iran's counterstrike capacity. 

Thus, the constraints imposed on US military operations by ammunition depletion on the defensive front would be substantially alleviated. Conversely, if Iran is able to preserve a degree of military production and retaliatory capacity, and continues to use relatively low-cost missiles and cheap drones to deplete US munitions stocks, the inventory of interceptor missiles deployed to protect forward bases in the Middle East and key sites of regional allies would become a major constraint on the sustainability of its military operations against Iran.

Such shortages may compel the US military to change its operational patterns, including setting interception priorities according to the threat level of incoming targets, increasing reliance on low-cost counter-drone measures, and even proactively narrowing protective coverage by foregoing the defense of non-essential assets. The direct consequence of such adjustments would be a significant escalation in risks faced by US forward bases in the Middle East and critical facilities of regional allies. This would not only undermine the credibility of US security commitments in the region, but would also rapidly accumulate political and military pressure on the Trump administration.

Trump could declare a 'win' and end the war

Prior to the start of this round of military strikes against Iran, diplomatic negotiations between the US and Iran were still progressing. Nevertheless, the terms demanded by the US were perceived by Iran as crossing its core red lines, and were never accepted by the Iranian side. Judging from the troop deployment and operational characteristics of the current campaign, the Trump administration has not demonstrated clear indication of deploying ground combat forces into Iran in the near future. It appears that its primary strategic intent is to leverage military superiority to forcefully reset the negotiation parameters and thereby compel Iran to accept more stringent restrictive terms.

In summary, the Trump administration has achieved the following short-term strategic objectives through strikes against Iran: the targeted elimination of Ayatollah Ali Khamenei and several senior leaders of the Islamic Revolutionary Guard Corps (IRGC), the substantial crippling of Iran's main naval combat capabilities, and the systematic weakening of Iran's conventional long-range strike capabilities. But the broader strategic goals the US seeks to advance through sustained military action – destroying Iran's nuclear capabilities, toppling the Iranian government, and gaining domestic support ahead of the US midterm elections – remain elusive.

Such objectives are difficult to accomplish through the medium of long-range strikes alone. When it comes to destroying Iran's nuclear capabilities, long-range strikes can inflict substantial damage on identified fixed nuclear facilities and specific critical research and development nodes. However, the protracted nature of the Iranian nuclear issue has resulted in Iran establishing decentralized, underground, and concealed nuclear facilities alongside backup systems. Relying solely on long-range strikes, the US military cannot comprehensively eliminate these facilities, let alone achieve the permanent destruction of Iran's nuclear capabilities.

Regarding a change in Iran's leadership, long-range strikes alone would be inadequate to deliver such an outcome unless the Iranian government was already in a state of collapse, with its legitimacy eroded and its governing system close to breakdown. This would require a considerable split among elites and extensive social mobilization on a large scale, coupled with opposition forces possessing armed capabilities strong enough to challenge the IRGC. In the absence of a deployment of US ground forces to Iran, long-range strikes are unlikely to help domestic opposition forces in establishing military capabilities comparable to the IRGC. Consequently, the objective of toppling the Tehran government proves difficult to achieve.

As for domestic support, the actual political consequences of this operation will depend on factors including its duration, the number of US casualties, and oil prices. At present, there is already substantial domestic criticism of the campaign. Even within the Republican Party and among MAGA supporters, questions have emerged over whether Trump is becoming overly aggressive and whether he is deviating from the "America First" principle. 

Even if the US were to deploy ground combat forces to Iran to fully intervene, these strategic objectives would still be difficult to achieve in the short term, provided that Iran does not undergo a severe elite split and political turmoil. Instead, such a move would risk embroiling the US in the very kind of war quagmire that Trump has repeatedly denounced in the past. Accordingly, the most viable strategic option for the Trump administration would be to sustain a period of limited strikes and then conclude this round of military operations by unilaterally declaring "mission accomplished" and "win."

The strategic objectives achieved in this round of military operations provide sufficient grounds for Trump to package political outcomes aligned with his "winning narrative," allowing him to present the campaign as a signature foreign and military achievement during his term in office. Also, ending the military operations would assist in the prevention of further erosion of US comprehensive national strength and prevent the further exhaustion of the Trump administration's political and diplomatic resources.

Under current conditions, the initiative for a ceasefire still lies with Trump. He could declare victory and implement a ceasefire at any time. Should Iran subsequently proceed with large-scale military retaliation, it would swiftly become the target of international criticism and diplomatic pressure. Such actions could provoke collective opposition and diplomatic pressure from neighboring Gulf countries, as well as many countries that depend on the security of shipping lanes through the Strait of Hormuz.