U.S. Air Force Pararescuemen conduct training on all aspects of combat, medical procedures and search and rescue tactics to hone their skills, providing the highest level of tactical capabilities to combatant commanders. Pararescuemen (also known as PJs) are United States Air Force Special Operations Command (AFSOC) and Air Combat Command (ACC) operators tasked with recovery and medical treatment of personnel in humanitarian and combat environments. These special operations units are also used to support NASA missions and have been used to recover astronauts after water landings. They are attached to other SOF teams from all branches to conduct other operations as appropriate. Of the roughly 200 Air Force Cross recipients, only 24 are enlisted rank, of which 12 are Pararescuemen. Part of the little-known Air Force Special Operations community and long an enlisted preserve, the Pararescue service expanded to include Combat Rescue Officers early in the 21st century.