It will start when one idiot believes he is the only side that will field the technology.
... then they run off an atomic battery. So they don't need to refuel.
... then they get discretion so they can make their own decisions.
... then they work as swarms with strategic thinking.
... then they decide anything with body heat is the enemy.
Somebody needs to start work on those pulse grenade plans built from easily sourced household materials.