Terminal guidance since ~1995 on higher-end weapons has switched to hybrid inertial + scene matching (various sensor types).
F.ex. the 90s Tomahawk used terrain contour matching to orient itself
For more details see https://apps.dtic.mil/sti/tr/pdf/ADA315439.pdf (US translation of a mid-90s Chinese survey of the guidance space, but it covers the material and is publicly available)
Afaik, most modern systems use infrared target matching for final course correction. (Initially developed to allow anti-shipping missiles to autonomously prioritize targets, but now advanced enough to use in land scenarios as well)
I don't think ATACMS or GMLRS missiles have any terminal guidance apart from their aim point. The GMLRS missiles that carry german SMART munitions do, technically, since the SMART munition has it's own targeting system.
It wouldn't make much sense to me, as most ATACMS warheads are area based, not point target based, so they wouldn't expect to aim at a single target. Also these systems are relatively cheap compared to things that DO have such guidance
F.ex. the 90s Tomahawk used terrain contour matching to orient itself
For more details see https://apps.dtic.mil/sti/tr/pdf/ADA315439.pdf (US translation of a mid-90s Chinese survey of the guidance space, but it covers the material and is publicly available)
Afaik, most modern systems use infrared target matching for final course correction. (Initially developed to allow anti-shipping missiles to autonomously prioritize targets, but now advanced enough to use in land scenarios as well)