The conflict has cost Washington around $29 billion, US Defense Department’s top budget official told Congress The Pentagon has raised its estimate of the cost of the Iran war to $29 billion, though the figure remains well below projections from several think tanks. In late April, acting Pentagon Comptroller Jules Hurst told lawmakers in Congress that the war had cost Washington around $25 billion. Testifying in a House Appropriations Committee hearing on Tuesday, Hurst revised the assessment,