The CBO report, which covers the period since the war began on February 28, lists 12 F-15E Strike Eagle fighter jets, one F-35A Lightning II jet, seven KC-135 Stratotanker aerial refuelling aircraft, and 45 MQ-9 Reaper drones among the 81 aircraft affected.
Harlan Ullman, a former naval officer and chairman of the Killowen Group, a government advisory firm, told Al Jazeera that the losses demonstrate how smaller militaries can inflict damage on larger forces. "The asymmetries of warfare show that even small countries with small militaries can inflict damage on the world's best militaries," he said. "Iran has plenty of US targets available, and you can imagine what a small drone can do to a major military asset."
The report comes as the conflict continues into its eighth month without a lasting ceasefire. Experts point to the evolving nature of modern warfare, where low-cost drones have become widely available and effective. Recent examples include the sudden departure of a dozen US aircraft from Royal Air Force Fairford in the UK over fears of a drone attack.
The rising costs of the war have also placed political pressure on the Trump administration. Earlier this year, the administration requested a record $1.5 trillion in defence spending for fiscal year 2027, citing the demands of the conflict. The price tag has sparked scepticism in Congress, particularly among Democrats.