I think also underappreciated is that Starlink can be used for purposes other than communication. It's already physically capable of acting as a giant radar, and SpaceX has gotten a missile tracking contract, and the E-7 wedgetail radar plane has been cancelled, which the DoD had publicly said was because it is obsolete given what's possible from space. It could be that they're planning on launching another radar constellation, but my guess is that it's already up there and it's called Starlink.
It's not clear to me that the radar is necessarily a separate constellation. SpaceX hasn't said a whole lot, but for example, SpaceX sells "Starshield" comms to the military, which uses the Starlink satellites for communications, except apparently the military has separate ground stations.
There's also been some published work where people have been talking about using Starlink signals passively for aircraft tracking. I'm not sure you couldn't use Starlink as a "stealth radar", in that the waveforms that are coming out of the satellites look like normal communications, but the satellites can also look at the echoes. Having the entire Starlink constellation form the radar is also pretty attractive from a cost and resiliency perspective since there are so many satellites to shoot down.
