Yeah exactly! Separation and dummy decoy warheads become an exponential problem and shooting through atmosphere is hard at hyper super mega sonic speeds. So in

Yeah exactly! Separation and dummy decoy warheads become an exponential problem and shooting through atmosphere is hard at hyper super mega sonic speeds. So interception in space but where, as you say. The only real 'near peer' nuclear threats are Russia and China so other than their 'boomers' (does China have that?) we should know which way they'll be coming from and their ballistic arc roughly. So we don't need global coverage 'just' GEO coverage of the parts we have intelligence on with pew pew laser line of sight which is of course lightspeed travel time and should be rapid aiming if there's enough of 'em. These might even be one shot weapons themselves perhaps even fission devices for the laser to have enough energy instantly available.