Kung Hsiang-sheng, associate researcher at Taiwan’s Institute for National Defense and Security Research, said such systems are extremely hard to implement in real life, however.

“Internet censors already filter and delete politically sensitive posts, but they have little ability to monitor happenings on the ground,” Kung said.

“The only way they would be able to prevent and detect such crimes is if the person announced they were planning to kill people in a school or on the street in advance, say in an online forum,” he said.

He said there is unlikely to be much prior warning of such crimes online.

“They can’t investigate anyone who sounds disgruntled on the internet,” Kung said. “It’s much harder to use technology to prevent crimes … that are carried out with no prior online warning.”

It sounds like they don’t actually have a Minority Report style prediction system that would work here, despite all their spying. Politicians like to say they have the solution to preventing violence even where effective solutions don’t exist.