Raytheon is looking at ways to respond to an urgent U.S. Navy call for a new version of the AIM-9X Sidewinder with greatly increased range, Vice President for Air Warfare Systems Harry Schulte said at the Paris air show June 19.

Although the Block II version of the missile is still in operational testing, the Navy wants to get the long-range Block III into developmental testing by 2018, according to budget documents.

The Block III “overlaps the range capability” of the AIM-120 Amraam, Schulte says.

Along with Navy efforts to add an infrared search and track system to the Super Hornet, it’s a response to “a particular threat that presents difficulties in RF” (radio-frequency). Asked whether the threat is Chinese, Schulte says “it could be.”

Boeing has said that the Hornet IRST program is a response to “RF-denied environments,” a likely reference to high-powered jamming. The new missile will use the Block II seeker, datalink and optical fuze but will almost certainly require a new motor.

“We could look at a fatter motor or a two-pulse motor,” Schulte says, possibly growing the weapon’s diameter from five to six inches.

Developing the motor raises challenges for Raytheon. Motor production at its previous Amraam motor supplier, ATK, has been shut down because inside and outside investigations have not found the reason why its motors started to fail cold-soak fires in 2010-11.

Amraam motors are now being built by Nammo in Norway, using a propellant based on the motor of the German-led IRIS-T infrared air-to-air missile, while ATK seeks a new propellant formulation. Raytheon is partnered with Rafael on the Stunner missile, which is under test and uses a Rafael-developed three-pulse motor. However, no formal talks with Rafael have taken place concerning the AIM-9X Block III.

According to budget documents, the Navy wants to award competing development contracts for new missile components by the end of fiscal 2013 and to start engineering and manufacturing development in fiscal 2014.