IIRC, most US precision/near precision munitions are dual navigation. For JDAM and GMLRS, for example, primary is INS backed up by GPS. GPS serves to update the weapon's INS fix just before launch/drop and subsequently while it is in-air. Loss of GPS means the weapon becomes progressively less precise the longer it takes to reach its target but is nonetheless still very accurate.
Complete loss of GPS might keep an INS/GPS-guided weapon from having the precision necessary to, say, dig out a hardened, buried command center or hit an individual SAM vehicle, but is still generally accurate enough to strike a designated building, logistics dump, field fortification, bridge, etc.