San Francisco’s ruling Board of Supervisors has voted to let the city’s police use robots that can kill.
The measure permits police to deploy robots equipped with explosives in extreme circumstances.
Dr Catherine Connolly, from the group Stop Killer Robots, said the move was a “slippery slope” that could distance humans from killing.
A spokesperson for the SFPD said “robots could potentially be equipped with explosive charges to breach fortified structures containing violent, armed, or dangerous subjects”.
They also said robots could be used to “incapacitate, or disorient violent, armed, or dangerous suspects who pose a risk of loss of life”.
Advocates for the measure said it would only be used in extreme situations.
Opponents, however, say the authority could lead to further militarisation of the police force.
Meanwhile, this type of lethal robot is already in use in other parts of the United States.
In 2016, police in Dallas, Texas, used a robot armed with C-4 explosive to kill a sniper who had killed two officers and injured several more.