[FtrPilot]

Some versions of the SDB have guidance systems using GPS/INS. These versions should be able to defeat GPS jammers. Accuracy would be degraded from 3 meters to 10 meters.

If there are any GPS only GLSDBs in Ukraine's inventory, they should be upgraded to GPS/INS guidance.

[ETCM]

The GBU-39 being used for the GLSDB has several options to get around GPS jamming, but we are unlikely to provide anything beyond the basic SDB. First, the DoD is upgrading many weapons to M-Code GPS receivers that are more resistant to jamming. Then there is the laser guided seeker GBU-39B/B version that has been demonstrated with GLSDB. You just need a drone to designate the target during the terminal guidance phase. Then there’s a Home On GPS-Jammer (HOG-J) seeker version of the GBU-39, though I’m not sure these are available in any number. Fire a couple of these a minute ahead of the attack to eliminate the jammers.

This article takes a wider look at the challenges of GPS jamming, and discusses some of the current solutions as well as some upcoming systems that will provide multiple alternatives.

https://spacenews.com/the-race-to-back-up-vulnerable-gps/