Iran and its allies have damaged at least 16 US military installations across eight Middle Eastern countries, rendering some of those positions virtually unusable, a CNN investigation has found.

The report drew on dozens of satellite images and interviews with sources in the United States and Gulf Arab nations. The damaged facilities constitute the majority of US military positions in the region, according to one congressional aide familiar with the damage assessments.

“There has been a spectrum of assessments,” the source said. “From a pretty dramatic side, of the whole facility is destroyed and needs to be shut down, to leaders who say these things are worth repairing due to the strategic benefit they give the US.”

Satellite images showed that Tehran’s main targets included advanced radar systems, communications systems and aircraft. Many of those assets are expensive and difficult to replace.

“It’s notable they really identified those facilities as the most cost-effective targets to hit,” the congressional aide said. “Our radar systems (are) our most expensive and our most limited resources in the region.”

On Wednesday, the Pentagon’s comptroller, Jules “Jay” Hurst III, told lawmakers that the Iran war has so far cost the US $25 billion. A source familiar with the matter later told CNN that the real cost estimate is closer to $40 to 50 billion.

US Gulf allies that host American military installations have borne the brunt of Iran’s attacks and have privately criticized Washington for starting the war without consulting them.

“The war showed us that the alliance with the US cannot be exclusive and it is not impregnable,” one Saudi source told CNN.