Billionaire Eric Schmidt says nightmare scenarios involving artificial intelligence will be a threat worth taking seriously within the next 20 years.

The former executive chairman of Google parent company Alphabet recently told an audience in Germany that AI fears inspired by science-fiction books and films are overblown -- for now.

Therefore, his advice during the Munich Security Conference held Feb. 16-18 was to "worry about them in a while."

"Everyone immediately then wants to talk about all the movie-inspired death scenarios, and I can confidently predict to you that they are one to two decades away. So let's worry about them, but let's worry about them in a while," he said, Defense News reported Wednesday. "You've been watching too many movies. Let me be clear: Humans will remain in charge of [AI] for the rest of time."

Mr. Schmidt's laissez-faire stance on the topic is at odds with other specialists in the field.

"I think we should be very careful about artificial intelligence," Space X CEO Elon Musk said in 2014 at the MIT aeronautics and astronautics department. "If I were to guess at what our biggest existential threat is, it's probably that. We need to be very careful with artificial intelligence. I'm increasingly inclined to think there should be some regulatory oversight at the national and international level just to make sure that we don't do something very foolish."

Softbank's Masayoshi Son's similar concerns prompted the Japanese CEO to put off retirement in June 2016 for "at least" another five years.

"Artificial intelligence will overtake human beings not just in terms of knowledge, but in terms of intelligence," he said then. "That will happen this century. … Looking into the next 30 years, our focus will no doubt be on AI, smart robots and the Internet of Things."

Mr. Schmidt of Alphabet told his German audience that AI will not be "reliable enough" for the foreseeable future to exist in any capacity besides "advisory" roles.

"These technologies [AI] have serious errors in them, and they should not be used with life-critical decisions," Mr. Schmidt said, Defense News reported. "So I would not want to be in an airplane where the computer was making all the general intelligence decisions about flying it. The technology is just not reliable enough ― there are too many errors in its use. It is advisory, it makes you smarter and so forth, but I wouldn't put it in charge of command and control."