The Russians Installed A GPS-Jammer In Ukraine. The Ukrainians Blew It Up—With A GPS-Guided Bomb.

GMLRS guidance package has access to military codes, so it's probably harder to jam

and beyond that, jamming doesn't matter that much unless you jam considerable length of missile path. if GPS signal is not available, it just switches to inertial. the later this happens and the better INS package is, the lower error you get

Doncha think?