The US Senate Armed Services Committee said its researchers had uncovered 1,800 cases in which the Pentagon had been sold electronics that may be counterfeit.
In total, the committee said it had found more than a million fake parts had made their way into warplanes such as the Boeing C-17 transport jet and the Lockheed Martin C-130J "Super Hercules".
It also found fake components in Boeing's CH-46 Sea Knight helicopter and the Theatre High-Altitude Area Defence (THAAD) missile defence system.
"A million parts is surely a huge number. But I want to repeat this: we have only looked at a portion of the defence supply chain. So those 1,800 cases are just the tip of the iceberg," said Senator Carl Levin.