The requirement for detailed integration because of proximity, fires or movement is the determining factor. CAS may need to be conducted during shaping operations with Special Operations Forces (SOF) if the mission requires detailed integration with the fire and movement of those forces. A closely related subset of air interdiction (AI), battlefield air interdiction, denotes interdiction against units with near-term effects on friendly units, but which does not require integration with friendly troop movements. The term "battlefield air interdiction" is not currently used in U.S. joint doctrine. CAS requires excellent coordination with ground forces. In advanced modern militaries, that coordination is typically handled by specialists such as Joint Fires Observers (JFOs), Joint Terminal Attack Controllers (JTACs), and forward air controllers (FACs).