Pentagon’s Iran war costs hit $38 billion in five months – budget office | 16 Sep 2026 | The U.S. war with Iran cost the Pentagon approximately $38 billion in its first five months, according to the Congressional Budget Office (CBO). The bill could rise by another $2 billion to $3 billion for every additional month of fighting — and by more if hostilities intensify. In a report released on Tuesday, the CBO estimated Defense Department expenses from the start of U.S. combat operations on February 28 through August 1. The figure includes the estimated cost of replacing expended munitions and equipment lost in battle, as well as additional flying hours, military operations, and higher fuel costs… The CBO estimates that replacing munitions used through August 1 would cost $21.7 billion, including $7.3 billion for land-attack cruise missiles, $13.1 billion for missile-defense interceptors and $1.2 billion for other weapons.