Marine Medium Tiltrotor Squadron 561 (VMM-561) is a medium-lift squadron of the United States Marine Corps flying the Bell-Boeing V-22 Osprey. Known as the "Pale Horse", it is part of Marine Aircraft Group 16 and based out of Marine Corps Air Station Miramar in California. They are scheduled to move to Okinawa in 2012... The squadron previously served as a training unit during the Vietnam War but was deactivated with the retirement of the HUSS from active service.