Lethal robots are not a technology that can really be regulated by ban.
It's not like nuclear weapons, where you need a huge industrial operation with tens of thousands of high-tech centrifuges running for years before you have enough fissile material for a bomb. Even the rulebreakers, like Israel, couldn't hide the fact that they were doing it and had to rely on America's UNSC veto to save them from the consequences.
But lethal robots are a trivial step away from the current state of robotics. Hobbyists have already mounted guns on quadcopters. Tesla and Waymo have made robots that kill people accidentally. Any robot can be made a killer robot with minimal change to its software and hardware.
It's not like nuclear weapons, where you need a huge industrial operation with tens of thousands of high-tech centrifuges running for years before you have enough fissile material for a bomb. Even the rulebreakers, like Israel, couldn't hide the fact that they were doing it and had to rely on America's UNSC veto to save them from the consequences.
But lethal robots are a trivial step away from the current state of robotics. Hobbyists have already mounted guns on quadcopters. Tesla and Waymo have made robots that kill people accidentally. Any robot can be made a killer robot with minimal change to its software and hardware.