The Fifth Fleet monitors the waters of the Gulf and keeps an eye on Iran.
"The crash was not due to any sort of hostile activity and the status of the five crew members is still being determined," the statement said.
Another MH-53E was on the scene to assist the search and rescue operation.
The US Navy has boosted its mine-sweeping operations in recent weeks in response to Iran’s repeated threats to close the Strait of Hormuz, through which a fifth of the world’s traded oil passes.
It was not immediately clear whether the helicopter that crashed, assigned to Helicopter Mine Countermeasure Squadron 15, was part of the reinforcements.
