I can see how this reduced drag on solid parts, but does it not also operate as an engine? The laser energy is projected forwards to hit molecules of air out in front of the aircraft. Those molecules are heated and so expand (the shockwave) but are they also not accelerated forwards? Yes, the laser is effectively pushing the air out of the way, but is that energy more or less than the energy needed to push the air away using mechanical force? Ie is putting energy into the laser more efficient than simply using that energy to increase the power of the engines?

In other words, rather than use the laser to expand air in front of the craft, would it be more efficient to use the laser to expand air in the engine to increase thrust?