[PaulHoule]

There is terminal defense against ICBMs and there is midcourse defense against hypersonics.

The ballistic warhead has little more to do than absorb the heat of reentry in the terminal phase. The energy to destroy it would be a good fraction of the energy that was in the rocket to begin with.

The hypersonic weapon on the other hand has to have sensors, effectors, and be unable to complete it's mission after receiving less beamed energy.

The airborne laser was killed not because it wasn't powerful enough (for some mission) but because the chemical laser it used was dangerous, expensive and otherwise impractical. The air force knew the army was developing modular fiber lasers so they decided to wait for that before building another platform, which could also be used against everything from drones to small ballistic missiles.

Hypersonic is just the cherry on top.

The alternative for interception hypersonics would be the nuclear-tipped ABMs of old, since the maneuvering capability of hypersonics defeats "hit-to-kill".