The Pentagon has previously said it has no evidence that Iran has been directing attacks on US forces in the region, and Tehran has repeatedly denied that it’s been involved in the operations.
A US official told CNN back in October that how willing the Shia militias were to act independently was always a “persistent intelligence gap,” meaning the US doesn’t know if Iran is directing their actions. Regardless, US officials have continued to blame Iran for the attacks in Iraq and Syria as well as for Houthi operations in the Red Sea.
https://archive.is/QaTlY