Project Excalibur was a Lawrence Livermore National Laboratory (LLNL) Cold War–era research program to develop an X-ray laser system as a ballistic missile defense (BMD) for the United States.
The concept involved packing large numbers of expendable X-ray lasers around a nuclear device, which would orbit in space.
During an attack, the nuclear device would be detonated, with the X-rays released focused by each laser to destroy multiple incoming target missiles
Hey at least something did came out of it: The most used weapon in the sci-fi Honorverse series.