An adversary would just shoot them down before launching ICBMs. Anti-satellite weapons are relatively cheap as they don't need to sustain orbit. Alternatively

An adversary would just shoot them down before launching ICBMs. Anti-satellite weapons are relatively cheap as they don't need to sustain orbit. Alternatively they can be hit early and Kessler syndrome can take down the whole constellation. Launching Brilliant Pebbles will just prompt a new arm race or trigger Armageddon.