The heavy expenditure of critical munitions in the Iran war has set off a deluge of headlines warning that US stockpiles are close to running dry. While certainly alarming, these tend to miss that this new conflict has simply exposed and accelerated a pre‑existing problem. The warning signs of a serious munitions shortage — and its impact on the US military — were apparent long before.

Since 2018, US strategic doctrine has acknowledged limitations on the scope of America’s engagement in international conflict, particularly given the resource demands of deterring conflict with China in the Indo‑Pacific, a US priority. However, leaders in Washington from both political parties have consistently refused to grapple with the hard choices that come with prioritisation.\n\nThe large‑scale drawdown of high‑value munitions from the US arsenal to arm Ukraine following Russia’s full‑scale invasion in 2022 robbed the war chest to the tune of approximately $67bn. Combined with the inability to replenish stocks quickly given significant industrial base constraints, the US traded away a significant degree of optionality.

The US intervention in Iran has only exacerbated these unfavourable conditions by further stressing munitions stockpiles already in deficit. Media reports estimate the depletion of nearly 80 per cent of the US Thaad inventory and close to half of Patriot interceptors. The supply of Tomahawks, a long‑range munition critical for a potential conflict in the Indo‑Pacific, is also estimated to have fallen by 50 per cent.

The Trump administration is now seeking a $1.5tn defence budget from Congress, as well as $73bn in additional supplemental funding just to address the costs of the war in Iran.\n\nWhile money and higher production targets look good on paper, they cannot speed up estimated delivery timelines. Even if requested funding and significant production increases break through the budget stalemate on Capitol Hill, the replenishment of critical munitions back to pre‑Iran war levels is years away. The notion that more money, more munitions and more time will always materialise permeates policymaking in Washington to an unhealthy extent.

This is evident in the very decision to start a war in the Middle East. President Donald Trump chose to do this despite inheriting a stressed and limited resource environment. Moreover, he appears to be keeping further escalation on the table.

False confidence only fuels strategic error. It cannot improve the inventory balance sheet. The pressure is mounting for the government to deliver both a defence budget and an Iran supplemental funding bill in September.

But rubber‑stamping eye‑watering levels of defence funding will not solve the problem. The Iran war has brought the structural and strategic limitations of the US military into focus, but reducing the munitions crisis to merely a symptom of this conflict alone misses the forest for the trees. The fundamental issue is that the US is overcommitted to the defence of other nations and cannot materially deliver in more than one theatre of conflict.

More money and better production targets without accompanying safeguards to protect American stockpiles all but ensure another munitions crisis in future. Congress, given its sole power over the purse, is the only branch of government that can require and enforce guardrails on the nation’s critical military resources. It should not move the defence budget or an Iran emergency supplemental forward without reinstituting and expanding protections on US munitions stockpiles.

It must ensure the US can meet and sustain its highest‑priority requirements first — resourcing a credible deterrence by denial approach in the Indo‑Pacific. Leaders on both sides of the political aisle no longer have the luxury of time to put off making difficult choices. On paper, the munitions shortages present a maths problem.

In practice, however, it is a strategic one. The defence budget and supplemental funding for Iran present a new opportunity to pivot back to a path of prioritisation. However, without acceptance of both strategic limitations and tighter guardrails around critical munitions, the US is doomed to repeat the cycle again under potentially far worse conditions.