U.S. Sen. Tammy Duckworth on Thursday sharply criticized the financial toll of combat operations against Iran, stating that a recent Congressional Budget Office estimate of $38 billion already spent represents a significant undercount of the true expense to American taxpayers.
In a post on X, the Illinois Democrat and combat veteran wrote:
“Let’s be clear: $38 billion is still a gross underestimate of what Trump’s illegal war has actually cost. And they’re expected to burn through $2 to $3 billion every month it drags on. Closed door briefings won’t cut it. Congress must hold a public hearing immediately.”
The statement came two days after the nonpartisan Congressional Budget Office released a detailed assessment requested by House Budget Committee Ranking Member Brendan Boyle. The agency calculated that Department of Defense operational, logistical, and sustainment costs for the conflict, known as Operation Epic Fury, reached approximately $38 billion as of August 1, 2026.
CBO found that replacing expended munitions accounted for the largest share at $21.7 billion, including $13.1 billion for missile defense interceptors and $7.3 billion for land-attack cruise missiles. Additional categories included $10.4 billion for increased flying hours, $2.7 billion tied to higher fuel prices, $1.9 billion for equipment lost in battle, and $1.5 billion for other operations costs.
The agency projected that if violence remained at the lower levels seen in May and June, each additional month would cost about $2 billion. A return to the higher intensity of July could push the monthly figure to $3 billion, with the potential for still greater expenses if fighting escalated further.
Duckworth has consistently described the conflict as illegal and unauthorized by Congress. She was among the early group of senators who repeatedly forced votes on War Powers Resolutions seeking to end hostilities, measures that were blocked multiple times.
In a September 15 press release, Duckworth highlighted a separate Department of Defense Inspector General quarterly report covering the first four months of the operation through June. That report put costs at $33.7 billion, including $22 billion on munitions and $184 million in damage to U.S. diplomatic facilities from Iranian strikes.
The senator noted that both the inspector general and CBO figures omit significant categories, such as the full cost of repairing damaged military bases and certain fuel expenditures, reinforcing her characterization of the $38 billion total as incomplete.
Operation Epic Fury began on February 28, 2026, with U.S. air and cruise missile strikes coordinated with Israeli operations. The administration stated its goals were to destroy Iran’s ballistic missile arsenal and production capacity, neutralize its navy, sever support for terrorist proxies, and prevent nuclear weapons development.
A ceasefire took effect on April 8, 2026, reducing the intensity of fighting for a period. On July 10, after Iranian attacks on tankers in the Strait of Hormuz, the president declared the ceasefire over. Combat operations have continued at varying levels of intensity since then.
CBO also examined opportunity costs, noting that heavy use of Patriot, THAAD, SM-3, and SM-6 interceptors has left the United States with a reduced inventory that could take at least five years to rebuild even with increased production. The agency warned this shortfall could complicate responses to potential conflicts involving larger missile arsenals, such as those held by China.
Economic effects identified by CBO include upward pressure on energy prices due to disruptions in oil and natural gas shipments through the Strait of Hormuz and related shipping interruptions in the Red Sea. The agency estimated that by the first quarter of 2027, year-over-year inflation in the personal consumption expenditures price index would be 0.5 percentage points higher than previously projected, with core inflation elevated by 0.3 percentage points.
Duckworth has pressed for greater transparency since the operation’s early days. She previously secured designation of the Defense Department inspector general as lead overseer for the conflict and has repeatedly called for public accountability rather than closed-door briefings.
On the same day as her X post, a group of Democratic senators, including Duckworth, sent a letter to Defense Secretary Pete Hegseth seeking a full breakdown of direct and indirect costs, details on a pending $67 billion supplemental request, and an accounting of prior funding.
The CBO letter to Boyle explicitly stated that its estimates for different cost categories rely on separate analyses and are not fully comparable or additive. It also noted that the figures exclude basic peacetime operating costs already in the budget, costs borne by other federal agencies, and longer-term expenses such as veterans’ care.
Defense Secretary Pete Hegseth had earlier testified that costs through September 2026 would total about $37.5 billion, a figure broadly consistent with CBO’s calculation for an earlier cutoff date. The administration had also requested $87.6 billion in supplemental appropriations in June, of which $67.1 billion was designated for the Defense Department.
Duckworth’s Thursday remarks underscored her longstanding position that the conflict lacks congressional authorization and continues to impose mounting financial and strategic burdens without sufficient public scrutiny.