"There is no theoretical perspective for economically viable boost-phase defense against the latest solid-fueled ICBMs, no matter if it would be ground-based missiles, space-based missiles, or airborne laser (ABL)."
https://en.wikipedia.org/wiki/United_States_national_missile_defense#Technical_criticism
Original Quelle_
https://www.aps.org/policy/reports/studies/upload/boostphase-intercept.PDF