Sector Nine was allegedly a division of the United States Air Force. While investigating the crash of Captain John Christopher's F-104 Starfighter in 1969, Aegis agent Gary Seven presented himself as an Air Force colonel in Sector Nine. (TOS - Star Trek: Assignment: Earth comic: "Yesterday, Today and Tomorrow")

It is unclear whether Sector Nine was a fabricated division, or whether it was a secret division the guard questioning Seven was unaware of.