The AIM-9X Sidewinder, developed by Raytheon engineers, entered service in November 2003 with the USAF (lead platform is the F-15C; the USN lead platform is the F/A-18C) and is a substantial upgrade to the Sidewinder family featuring an imaging infrared focal plane array (FPA) seeker with claimed 90° off-boresight capability, compatibility with helmet-mounted displays such as the new U.S. Joint Helmet Mounted Cueing System, and a totally new three-dimensional thrust-vectoring control (TVC) system providing increased turn capability over traditional control surfaces. Utilizing the JHMCS, a pilot can control the AIM-9X missile by simply looking at a target, thereby increasing air combat effectiveness. It retains the same rocket motor, fuze and warhead of the "Mike," but its lower drag gives it improved range and speed. AIM-9X also includes an internal cooling system eliminating the need for use of nitrogen bottles (U.S. Navy and Marines) in the launch rail or argon internal bottle (USAF). It also features an electronic safe and arm device similar to the AMRAAM allowing reduction in minimum range and reprogrammable InfraRed Counter Counter Measures (IRCCM) capability that coupled with the FPA provide improved look down into clutter and performance against the latest IRCM. Though not part of the original requirement, AIM-9X has demonstrated a Lock on After Launch capability, allowing for possible internal use for the F-35, F-22 Raptor and even in a submarine launched configuration for use against ASW platforms. Combined with the Joint Helmet Mounted Cueing System this delivers combined kill ratios exceeding 50:1 against nonhigh-off-boresight equipped fighters.
As of September 2008, Raytheon has delivered 3,000 AIM-9X missiles to the armed services and has begun testing the Block II version of the missile.The Block II adds lock on after launch and a datalink so the missile can be launched first and then directed to its target afterwards by an aircraft with the proper equipment for 360 degree engagements, such as the F-35 and F-22.