Oof
Anyone want to do the math to see how high something would have to be to be able to see it from 400km away?
So now, anyone want to do the math on the yield you'd need to make a mushroom cloud that high (they seem to specify not nuclear too)?
Ala_Huckbar:An estimate is sqrt(r^2+400^2)-r^2. It comes to about 12km.