The 121st Fighter Squadron is a tactical unit within the U.S. Air Force. This squadron, part of the Massachusetts Air National Guard, operates the F-15 Eagle fighter aircraft. Established in 1946, it has a long history of service to the United States and has been deployed multiple times, including during Operation Iraqi Freedom. The squadron’s primary role is air defense and its base of operations is Barnes Air National Guard Base, Westfield, Massachusetts. The 121st Fighter Squadron operates under the 104th Fighter Wing and is a component of the Air Combat Command.