Hughes has won its battle with Raytheon to provide the US Navy and US Air Force with replacement short- range air-to-air dogfight missiles.
The US Naval Air Systems Command, which led the AIM-9X, selected the Hughes Evolved Sidewinder bid, a decision which provoked confusion and consternation among the competition.
Both Hughes and Raytheon offered two bids, one based around the 127mm Sidewinder body, the others around larger diameter rocket motors for increased kinematic performance.
Using the 127mm-diameter airframe will allow Hughes to use existing AIM-9 solid rocket motors.
Hughes had teamed with British Aerospace in offering a modified Advanced Short-Range Air-to-Air Missile, while Raytheon was offering a version of its AIM-9X design with the 162mm Rafael Python Four motor.
Sources close to the competition are surprised at the decision. Given the perceived kinematic-performance limitations of the Evolved Sidewinder, some have speculated that the choice reflected an "interim solution", pending the emergence of an unrevealed "black programme".
One source suggests that the US Navy is working on a 160mm-plus motor design.
BAe had been hoping that the US Department of Defense would overcome its "not invented here" phobia on major programmes in deciding to purchase the ASRAAM P3I. One official greeted the outcome by saying "-it appears politically impossible for the USA to purchase outside the country".
Other sources suggest that the US Navy is concerned about the ASRAAM motor's thrust profile.
Hughes had also been hoping to use an ASRAAM P3I selection as leverage in the UK Ministry of Defence's (MoD's) competition for a future medium-range air-to-air missile (FMRAAM), holding out the olive branch of transatlantic collaboration on an AIM-120 advanced medium-range air-to-air missile derivative.
UK MoD sources have expressed disappointment with the US decision, and admit that it will not further dispose the MoD to a US solution for the FMRAAM.
The Evolved Sidewinder uses the existing Sidewinder motor, coupled with thrust-vector control to achieved the desired manoeuvrability for high off-boresight engagements.
Some missile specialists, however, harbour doubts as to whether the missile will have enough residual energy "once it has got round the corner" to engage a manoeuvring target in the more demanding combat scenarios.