A Navy spokesperson said the sailor was not located during a search aboard the carrier.
"The aircraft carrier USS Nimitz (CVN 68) and guided-missile cruiser USS Princeton (CG 59) are currently conducting search and rescue operations in the North Arabian Sea following reports of a missing US Navy Sailor, Sept. 6," according to a statement from the US Navy's 5th Fleet.
The search for the missing sailor reportedly continued after darkness fell in the region.
"The sailor was not located upon a search on board which resulted in a man overboard being called and the activation of the search and rescue," Cmdr. Rebecca Rebarich, a 5th Fleet spokesperson told ABC News.
The Navy has refused to release the identity if the sailor, listing him as Duty Status Whereabouts Unknown (DUSTWUN).
“The sailor has been listed as duty status whereabouts unknown (DUSTWUN) onboard Nimitz, read the statement. “The sailor’s name is being held in accordance with US Navy policy. Updates will be provided as they become available.”
There are reportedly between 5,000 and 8,000 sailors on the ship.