USAF’s Stand-In Attack Weapon (SiAW) is based on the extended-range version of the US Navy’s Advanced Anti-Radiation Guided Missile (AARGM) in development at Northrop Grumman.
The so called Stand-In Attack Weapon (SiAW) is moving forward. The US Air Force (USAF) in fact will check how it fits inside the F-35 Lightning II next summer.
The service spokeswoman Ilka Cole said recently the F-35 is currently the only USAF aircraft under consideration for the weapon even though the Air Force previously said the missile would fly on the B-21 as well. Fit checks will entail wind tunnel testing and ground tests.
According to Air Force Magazine the SiAW is based on the extended-range version of the Navy’s Advanced Anti-Radiation Guided Missile (AARGM) in development at Northrop Grumman. Cole said missile design specifications like its range are classified.
The weapon will most likely be used to get closer to countries that keep out encroaching aircraft and to take out enemy systems that target the key assets of modern war, like GPS and other satellites. It’s designed to pursue targets that move quickly as well.

“SiAW targets include theater ballistic missile launchers, land attack and anti-ship cruise missile launchers, GPS jammers, anti-satellite systems, and integrated air defense systems,” according to Air Force budget documents.
Northrop Grumman’s AARGM is a supersonic, air-launched tactical missile system. It has the capability to perform Destruction of Enemy Air Defense missions and is an upgrade to the US Navy AGM-88 HARM system. AARGM is able to rapidly engage traditional and advanced land- and sea-based air defense threats, as well as non-radar, time-sensitive strike targets. The baseline version is already integrated onto the F-35.
The SiAW will be vet on the F-35 in the early 2020s so it can begin regular operations by the mid-2020s. It’s expected to wield a new warhead, the design of which is slated to end in fiscal 2021.
The Air Force created the program in 2018 and requested $160.4 million for SiAW development in its 2021 budget, ramping up to $364.5 million in 2025. The request did not say how much the weapon will cost in total.

Photo credit: Senior Airman Christopher Callaway / U.S. Air Force and Letterkenny Munitions Center