Early reports indicate that the pilot of a US F-15 fighter aircraft downed over Iran was rescued - which, if confirmed, would be the latest in the long history of US combat search-and-rescue missions over decades.

The search operation is ongoing deep inside Iran for a second crew member, according to CBS, the BBC's US partner.

Combat search and rescue (CSAR) missions are considered among the most complex, time-sensitive operations that US and allied militaries prepare for.

In the US, elite units of the air force are specially trained for CSAR missions and are often pre-emptively deployed near conflict areas where aircraft could be lost.

Verified video that emerged from Iran on Friday appeared to show US military helicopters and at least one refueling aircraft operating over Iran's Khuzestan province.

As Iranian officials urge citizens to locate the missing US crew member, emphasizing the political stakes, the rescue mission highlights the intricate dynamics of military operations within hostile environments.