Armies of Terminator-like warriors fan out across the battlefield, destroying everything in their path, as swarms of fellow robots rain fire from the skies.
That dark vision could all too easily shift from science fiction to fact with disastrous consequences for the human race, unless such weapons are banned before they leap from the drawing board to the arsenal, campaigners warn.
Starting today, governments are holding the first-ever talks focused exclusively on so-called "lethal autonomous robots".
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The four-day session of the UN Convention on Conventional Weapons in Geneva could chart the path towards preventing the nightmare scenario evoked by opponents, ahead of a fresh session in November.
"Killer robots would threaten the most fundamental of rights and principles in international law," warned Steve Goose, arms division director at Human Rights Watch.
"We don't see how these inanimate machines could understand or respect the value of life, yet they would have the power to determine when to take it away," he told reporters on the eve of the talks.
"The only answer is a preemptive ban on fully autonomous weapons," he added.
Goose's organisation came together with a host of others to form the Campaign To Stop Killer Robots in April 2013, prodding nations into action.
Robot weapons are already deployed around the globe.
The best-known are drones, unmanned aircraft whose human controllers push the trigger from a far-distant base. Controversy rages, especially over the civilian collateral damage caused when the United States strikes alleged Islamist militants.
Perhaps closest to the Terminator-type killing machine portrayed in Arnold Schwarzenegger's action films is a Samsung sentry robot used in South Korea, with the ability to spot unusual activity, talk to intruders and, when authorised by a human controller, shoot them.
Then there is the Phalanx gun system, deployed on US Navy ships, which can search for enemy fire and destroy incoming projectiles all by itself, or the X47B, a plane-sized drone able to take off and land on aircraft carriers without a pilot and even refuel in the air.
Other countries on the cutting edge include Britain, Israel, China, Russia and Taiwan.
But it's the next step, the power to kill without a human handler, that rattles opponents of lethal autonomous robots the most.
"Checking the legitimacy of targets and determining proportional response requires deliberative reasoning," said Noel Sharkey, emeritus professor of robotics and artificial intelligence at Britain's University of Sheffield.
