A U.S. Air Force (USAF) F-35A Lightning II stealth fighter squawked emergency transponder code 7700 while flying over the Sea of Oman near the Strait of Hormuz, Iranian state media outlets Fars News Agency and Tasnim reported.
The code indicated an immediate emergency requiring landing, the media reported.
The cause of the emergency was not immediately clear.
Transponder code 7700 is a standard international aviation emergency squawk used to indicate a general in-flight emergency requiring immediate priority and assistance from air traffic control.
Its activation does not in itself identify the nature of the emergency, which can range from mechanical failure to medical incidents to combat damage.
Iranian state media cited the squawk as occurring moments before the respective reports were published.
Neither Fars nor Tasnim provided additional details on the aircraft's subsequent status, final location, or the outcome of the emergency.
No immediate U.S. military statement on the incident was available at the time of reporting.