US spent billions on a 24 hour flying 747 with a laser nose cone. It was retired, did not work. Remember that?
It actually did work, but it was killed for two good reasons. 1) Atmospherics prevented it from taking out a launched missile from a safe standoff distance, i.e. it would have been shot down by North Korean missiles before it could get within the weapon effective kill distance to take out an ICBM launch. 2) By the time the testing was complete, the optics, lasers, and technology used were 20 years behind what could be fielded now, with far less weight, volume, and greater power.