In 1993 I saw a complete ground-based anti-satellite laser system in New Mexico that had everything to burn a satellite except for the laser (aka. "optical tracking system") It actually did have a 25W laser that excited a "sodium guide star" in the upper atmosphere that controls a mirror that undoes atmospheric twinkling and is necessary if you want to uplink laser energy with high efficiency.
That's nothing - in 1985 I saw a demo for an orbital 5 megawatt laser.