What NORAD modernization is meant to be doing is a system-to-system approach using surveillance that is satellite-based, land-based, under the sea and above the sea. It has to be all-encompassing to be effective. Instead of using a stovepipe approach to look at each domain, the AI and the technology allows us to have them all interconnected. We can get a multi-spectrum picture from all the systems available.
As far as a defending system is concerned, defending a satellite in space is problematic, but there is always a ground station somewhere that needs to be protected.