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 dollars will be required to replace spent ammunition, and another 6 billion dollars for lost and damaged military equipment, including planes and UAVs. The calculations apparently do not fully account for the cost of repairing American bases damaged by Iranian missile and drone attacks.