The US spent 47 billion dollars on the war with Iran. Reuters According to the agency, the US military spent more than 47 billion dollars on the war with Iran. That's a quarter more than the Pentagon's July estimate of $37.5 billion. Of this amount, more than $29 billion will be required to replace spent ammunition, and over $6 billion more for lost and damaged military equipment, including aircraft and UAVs. The calculations apparently do not fully account for the costs of repairing American bases damaged by Iranian missile and drone attacks.