DALLAS/HOUSTON/LOS ANGELES/WASHINGTON – When Dallas police improvised a bomb-carrying robot to kill a sniper, they also kicked off an ethical debate about technology's use as a crime-fighting weapon. In what appears to be an unprecedented tactic, police rigged a bomb-disposal robot to kill an armed suspect in the fatal shootings of five officers in Dallas. While there doesn't appear to be any hard data on the subject, security experts and law enforcement officials said they couldn't recall another time when police deployed a robot with lethal intent. The strategy opens a new chapter in the escalating use of remote-controlled and semi-autonomous devices to fight crime and protect lives. It also raises new questions over when it's appropriate to dispatch a robot to kill dangerous suspects instead of continuing to negotiate their surrender.

When a police robot killed suspect Micah Johnson in Dallas early Friday morning, it was likely an unprecedented event. But according to Steve Ijames, recently retired assistant chief of police in Springfield, Missouri, and a recognized expert in SWAT tactics, it was not a watershed moment portending a weaponized robotic future. The standoff after the police massacre at a Black Lives Matter protest was unique for a number of reasons, he says. And it was likely the only choice the police had. The police department hasn't elaborated on the device the bomb-defusing robot used or how exactly it killed the suspect, nor on the circumstances that led to the decision.

After sniper fire struck 12 police officers at a rally in downtown Dallas, killing five, police cornered a single suspect in a parking garage. After a prolonged exchange of gunfire and a five-hour-long standoff, police made what experts say was an unprecedented decision: to send in a police robot, jury-rigged with a bomb. "We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was," Dallas Police Chief David Brown told a news conference Friday. "Other options would have exposed our officers to grave danger. The suspect is deceased as a result of detonating the bomb."

The same type of bomb-carrying robot that Dallas police used to kill a sniper who shot and killed five officers during a Black Lives Matter rally could easily be fashioned and deployed by dozens of other police forces across the country. The robot that officers used to kill Micah Xavier Johnson is designed to find and disarm bombs, not deliver them. Robotics experts said the incident was the first time law enforcement has used a robot in a targeted killing in the U.S. These bomb-detecting robots are fairly inexpensive, often costing less than 10,000 each. But local, state, and federal law enforcement agencies can also request the devices at no cost through the military's 1033 program, which gives used military equipment that would otherwise be thrown away to U.S. law enforcement agencies.

In May, a Tesla TSLA 0.39 % "autopilot" enthusiast in Florida became the first known fatality in a self-driving car. But this was no ordinary accident. The car performed exactly as designed, and the (non)driver's failure to take any corrective action could reasonably have been foreseen by the manufacturer. This unwelcome yet widely anticipated milestone may set back progress on what promises to be one of the most valuable technologies of the 21st century. In its rush to get hot new products into consumers' hands, Tesla--along with many other car manufacturers--has pursued a flawed vision of the future, one in which tomorrow's technology is simply layered on top of today's.

A robot carrying an explosive device was used to kill one of the shooters in Thursday night's horrific violence in Dallas, Texas, in what many law enforcement and other experts are calling the first such use of robotics technology by U.S. police. Five police officers were killed and seven others were wounded, along with two civilians, during a demonstration protesting the recent deaths of two African-American men at the hands of police in other cities. Micah Johnson, the man suspected of shooting the officers, was killed by remotely detonated explosives on the robot after a standoff and failed negotiations with police. Toby Walsh, a professor of artificial intelligence at the University of New South Wales, cautions against seeing this use of a robot as a nightmarish science-fiction scenario--because the robot was being operated by a human via remote control. "In [that] sense, it was no more taking us down the road to killer robots than the remote-controlled Predator drones flying above the skies of Iraq, Pakistan and elsewhere," Walsh told Scientific American in an email.

Several hundred people filled Thanks-Giving Square in downtown Dallas on Friday for an interfaith service hosted by dozens of clergy. A rabbi spoke, then an imam, a Methodist and a Baptist. A dozen uniformed police looked on, wearing black bars over their badges in honor of their fallen comrades. Mayor Mike Rawlings reminded the crowd when the square was erected: in 1964, a year after President John F. Kennedy was assassinated here, a bloody legacy that would haunt the city for decades. In recent weeks, people gathered in the square to mourn victims of the mass shooting in Orlando, Fla.

Less than 12 hours after a sniper killed several police officers in Dallas, three dozen fresh-faced recruits sat solemnly in dark-blue uniforms outside the Los Angeles Police Department's downtown headquarters, staring straight ahead during a graduation ceremony marking the end of their journey to become fully-fledged cops. "Today was supposed to be a happy day," L.A. Mayor Eric Garcetti told them. "But we come here today with tears in our hearts, with hearts that are broken." Thursday night's attack in Dallas hung over the LAPD's graduation ceremony Friday morning, the pomp and circumstance clouded by concern. One veteran officer's eyes welled with tears as he talked about the attack.

A 13-year-old in California shook her head at the TV. A 5-year-old in Pittsburgh asked her father why people are so angry. As America coped with one tragic moment after another this week, with the deaths of Alton Sterling and Philando Castile followed by the shooting of a dozen police officers in Dallas, the country's parents had an added task: explaining each act of violence to their children. "If [children] see a bunch of this on television, they can become the indirect victims of trauma," said Suzanne Silverstein, director of the Cedars-Sinai Psychological Trauma Center. African American children might be afraid for their own lives or for their friends and families when they see black men being shot.

Negotiators had been talking for hours with the hunkered-down killer of five police officers in downtown Dallas when the man suddenly resumed firing with an assault rifle. Fearing additional casualties, the officers deployed a small, remote-controlled robot to carry an explosive device near shooter Micah Xavier Johnson, which they then detonated, killing him. "We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the suspect was," Police Chief David Brown said at a news conference Friday morning. "Other options would have exposed our officers to grave danger .… We have confirmed that he's been deceased because of the detonation of the bomb."