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US Iran war cost hits $29bn on 12 May

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Bloomberg and CBS News reported on 12 May that the US war against Iran has cost $29 billion, up $4 billion from the $25 billion figure the Pentagon briefed to Congress two weeks earlier. None of the spending has a signed presidential instrument behind it.

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Key takeaway

Bloomberg and CBS put the US Iran war cost at $29bn on 12 May, $4bn above the Pentagon's figure.

Bloomberg and CBS News reported on 12 May 2026 that the US war cost against Iran has reached $29 billion, up $4 billion from the $25 billion figure the Pentagon briefed to Congress approximately a fortnight earlier ¹. The figure landed on the same day Pete Hegseth told Senate Appropriations that Article 2 covers Iran strikes and no AUMF is required, a juxtaposition that puts $4 billion every two weeks alongside zero signed presidential instruments.

$4 billion fortnightly is the build cost of a Virginia-class submarine every two weeks, sustained for 75 days without a vote, a finding, or a signed executive order. The operational layer behind the burn rate is CENTCOM's blockade, which had logged 61 cumulative vessel redirections and four disabled vessels by 10 May . The constitutional layer is now Article 2 alone. Trump's contradictory 8 May Truth Social posts and his 11 May Oval Office military-options list are the rhetorical surface of the same unsigned arithmetic.

Senate Appropriations becomes the only operating venue for legislative pressure on Iran policy because, under the administration's stated reading, appropriators can defund but cannot deauthorise. Murkowski's unfiled AUMF sits between a $4 billion fortnightly burn rate the appropriators can in principle constrain and a doctrine telling them they cannot deauthorise it.

Deep Analysis

In plain English

The United States has spent $29 billion fighting in Iran since the war began on 28 February. Bloomberg and CBS News reported that figure on 12 May. To put it in perspective: the cost of building a nuclear submarine is roughly $4 billion, and the US is spending that amount every two weeks on this conflict. When governments go to war, they normally pass special legislation, called an Authorisation for Use of Military Force, that both approves the war and sets a budget. In this case, Congress has passed no such authorisation. The money is being spent under normal Pentagon budget authority, which the Senate Appropriations Committee oversees. That committee, the one that writes the military's annual budget, is now the main place in Congress where any attempt to question or limit the war can actually happen. The committee cannot formally vote to end the war without the authorisation it was denied, but it can refuse to approve new war spending.

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Primary parallel: The early Korean War offers the structurally closest precedent: Truman committed forces in June 1950 under UN Security Council authority without seeking congressional authorisation, and the war cost approximately $30 billion in 2026 dollars before Congress passed its first relevant appropriation.

The 2003 Iraq War cost $53 billion in its first year, but that spending was authorised by a formal AUMF passed by Congress on 16 October 2002; the Iran campaign's running Total across 75 days is on a comparable monthly trajectory with no such instrument behind it.

Counter-parallel: The 1991 Gulf War cost $61 billion Total, with allied burden-sharing covering $48 billion of that. The Iran campaign has no comparable allied cost-sharing mechanism; the European coalition is building a separate post-war framework but has not contributed to CENTCOM's operational costs, leaving the entire war bill on the US Treasury alone.

The $4 billion fortnightly burn rate maps onto specific CENTCOM cost drivers that defence economists have publicly modelled. A Carrier Strike Group in operational tempo costs approximately $25 million per day.

Two CSGs in the Gulf run at roughly $3.6 billion over 75 days before adding TLAM (Tomahawk Land Attack Missile) stocks, JASSM (Joint Air-to-Surface Standoff Missile) procurement to replace expended rounds, aerial refuelling, and SOF (Special Operations Forces) logistical support. The Total war-cost figure implies the kinetic campaign has consumed approximately $10-12 billion in munitions and replenishment procurement on top of operating costs.

The constitutional asymmetry sharpens the fiscal significance. Senate Appropriations can cut the OCO (Overseas Contingency Operations) transfer or refuse a supplemental appropriations request; these are the practical tools for constraining a war the executive branch claims it needs no authorisation for.

The $4 billion fortnightly rate gives appropriators a concrete figure to defund in the next continuing resolution or supplemental. Senator Collins, who chairs Senate Appropriations and sat on the panel where Hegseth testified, has the authority to attach conditions to the next Pentagon spending instrument even if she cannot file an AUMF.

Sources:Foreign Policy Journal·Foreign Policy Journal

Mentions:CBS News →Donald Trump →CENTCOM (US Central Command) →Truth Social →United States →AUMF →Virginia →Iraq →Iran →US Treasury →Pete Hegseth →Senate Appropriations Committee →Gulf War →Pentagon →Bloomberg →

First Reported In

Update #96 · Hegseth: no AUMF needed. Trump flies east

Foreign Policy Journal· 13 May 2026

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Causes and effects

Caused by

CENTCOM redirections rise to 61, disabled count holds at four

CENTCOM's 61 cumulative redirections (ID:3211) are the operational context for the $29bn war cost now reported by Bloomberg and CBS

Occurred 10 May 2026

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This Event

US Iran war cost hits $29bn on 12 May

A $4 billion fortnightly burn rate with no signed authorisation behind it gives appropriators the leverage that authorisers no longer have under Hegseth's Article 2 reading.

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