The Air Force has not fully implemented the recommendations from GAO's 2009 report. With regard to GAO's recommendation that the military services should formally assign ASA duties to the units that consistently conduct them and ensure that the readiness of those units is fully assessed, the Air Force did so. However, the National Guard Bureau is considering reversing that action because it believes that the recommendation can be better addressed through the Air Force's standard deployment process. The Air Force has also not established a timetable to implement ASA as a steady-state mission; has not developed and implemented a plan to recapitalize the aging fighter aircraft that conduct ASA operations before the end of their service lives; and, when ASA units are deployed to support other ongoing operations, the Air Force continues to identify replacement units to perform the ASA mission on an ad hoc basis. All of the above were related to recommendations GAO made to the Air Force in its 2009 report. Separately, GAO found considerable confusion about the capabilities associated with ASA operations in part because, in September 2011, NORAD stopped using the term "air sovereignty alert" and created a new term, "aerospace control alert" (ACA), without clearly defining ACA or the missions that are now included within it.