[PaulHoule]

The main trouble with ground-based is clouds, that is what makes you go airborne.

I could picture planes in the air 24-7 circling around vulnerable points, or being dispatched on warning. Either way it would be expensive but would be awesome.

[mustacheemperor]

>I could picture planes in the air 24-7 circling around vulnerable points

The US previously spent a few billion and 16 years on that exact idea as part of the SDI, before canceling it a few years after the first working tests because, to quote the Defense Secretary,

>I don't know anybody at the Department of Defense who thinks that this program should, or would, ever be operationally deployed. The reality is that you would need a laser something like 20 to 30 times more powerful...there's nobody in uniform that I know who believes that this is a workable concept[0]

If the laser power was a problem, maybe Raytheon's tech will make the concept more plausible. The wikipedia article says there's been some additional experimentation mounting lasers on UAVs since the program was cancelled.

[0]https://en.wikipedia.org/wiki/Boeing_YAL-1

[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".