I work on industrial lasers, the idea of using it as a long range weapon is crazy to me. the sophistication required to keep the beam collimated over a distance like that to still pack a lethal punch must be insane.
Chris Knight solved that problem almost 40 years ago. It is possible to synthesize excited bromide in an argon matrix. It's an excimer, frozen in its excited state. A chemical laser but in solid, not gaseous, form, capable of extracting at least ten to the twenty-first photons per cubic centimeter which gives one kilojoule per cubic centimeter at 600 nanometers, or, one megajoule per liter.