“I don’t think 100 kW would be enough to zap cruise missiles out of the sky, (but) 100 kW — and even lower — may be sufficient to blind/degrade some weapon sensors,” causing them to miss, said directed energy expert Mark Gunzinger, of the Center for Strategic & Budgetary Assessments.
“There are quite a few targets 60-100 kW lasers could be used to degrade or defeat, including rockets, artillery rounds, some missiles, UAVs (Unmanned Aerial Vehicles), etc.,” Gunzinger told me in an email. “We are talking short ranges for ground-based 100 kW-class lasers to achieve ‘burn-through’ kills on UAVs or rockets, (but) sometimes a functional kill — blinding or burning out a sensor a weapon uses for final guidance to a target — is good enough.”
“For missile defense, some consider 300 kW an important threshold for countering some types of cruise missiles, assuming the attack geometry requires a head-on shot (because) the cruise missile is coming directly at a defended asset,” Gunzinger told me. “Lower power lasers may be effective against the softer sides of cruise missiles.” Getting side shots would probably require a network of lasers around any given target to ensure at least one could get the right angle on an incoming weapon. That said, he emphasized, “I’m skeptical that 100 kW would be sufficient for CMD (cruise missile defense), even with side shots.”