The US Air Force has been the first to respond to growing reports that Russian EW jamming is severely impacting the effectiveness of Ukraine’s Western-supplied GPS-guided munitions, including the Joint Direct Attack Munition-Extended Range (JDAM-ER) precision-guided glide bombs that have been in use since early 2023 deployed on Kyiv’s Soviet-era MiG-29 “Fulcrum” and Su-27 “Flanker” fighters.

The Pentagon announced on Friday that the US Air Force had awarded the US company Scientific Applications and Research Associates Inc (SARA) a contract valued at round $23.5 million for the provision of seekers that would allow existing JDAM-ER kits to be modified to home in on the sites where GPS jammers were operating. The seekers would be provided as Foreign Military Sales (FMS) to Ukraine.


Little detail about the method of operation and effectiveness of the SARA seeker system has been made available, but it is known that the company has been developing the capability for integration with a variety of precision-guided munitions for several years.

The system is designed to identify the location of any radio frequency (RF) emitters on the battlefield and then guide the host missile or bomb to engage the source. Targets can include air-defense radars as well as jamming systems.

According to the defense issues website The War Zone, the US Air Force trialed prototypes of the SARA HOJ (home-on-GPS-jam) seeker alongside development of the GBU-39/B Small Diameter Bombs (SDB) in December 2020. Those tests suggested that the HOJ technology could be applied to other Western-supplied precision-guided munitions.

‘Ramstein’ Ukraine Defense Contact Group to Meet on May 20: Pentagon
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‘Ramstein’ Ukraine Defense Contact Group to Meet on May 20: Pentagon

The 22nd Meeting of the Ramstein Group will be on May 20 with options to watch US Secretary of Defense Austin’s opening remarks by livestream.

Bill LaPlante, US Under Secretary of Defense for Acquisition and Sustainment highlighted the issue of GPS jamming on unspecified weapon systems at a Center for Strategic and International Studies (CSIS) seminar a week ago. Daniel Patt told the US House Armed Services Committee in March that Russian EW had reduced the accuracy of the 155mm Excalibur precision artillery munition, which uses a GPS guidance package, from around 70 to 6 percent efficiency.


Russia has claimed that its GPS jamming capability was also degrading HIMARS and ATACMS accuracy as well as existing JDAM-ERs and is also using such technology to protect Kaliningrad, which has interfered with GPS systems used by commercial aviation in the Baltic regions and areas of Poland.

Giving Ukraine the capability to direct its missiles and aerial bombs against the source of such GPS interference will make the users of that jamming technology reluctant to deploy them at the risk of being rapidly eliminated.

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