I think this post is more focused on nuclear defense in space. Which also changes the whole mutually assured destruction dynamic. Until 2002 we were in a treaty that limited anti-ballistic missile systems
Yes, SpaceX is said to be developing something more akin to Brilliant Pebbles, eventually using kinetic interceptors like https://castelion.com is developing. (team at company are all SpaceX starshield people). Intercepts ICBM in "boost phase" launching from enemy territory (vulnerable / no decoys possible). Mike Griffin is Castelion advisor (enough said) https://en.m.wikipedia.org/wiki/Michael_D._Griffin#Career