First, there were autonomous cars. Now, there are autonomous… submarines?

China is developing a fleet of unmanned submarines that could be used for everything from surveillance to attacking other ships and subs. The “autonomous robotic submarines” -- essentially large underwater drones -- may be roaming the world’s oceans in the 2020s, according to the South China Morning Post.

Pictured here is one of China’s previous unmanned autonomous underwater vehicles, the Qianlong No. 3. (Picture: Xinhua)

The seas have become the new “playground of the superpowers” thanks to vast amounts of untapped natural resources and energy.

One of the most contested areas is the South China Sea, and it’s here that researchers say the subs will likely be deployed to help counter efforts by Western powers -- who are in turn trying to counter militarization efforts by China.

How do they work?

Powered by diesel-electric engines that can run for months, the devices are designed to work with little or no human interaction.

They will instead rely on artificial intelligence to help them make decisions, including navigating crowded waters and avoiding detection. They won’t replace fully-sized submarines, but are designed to work alongside them for missions. They can deploy mines and act as decoys for enemy subs.

And they might even go a step further.

“It can even perform a kamikaze strike,” a Chinese researcher told SCMP.

What about other countries?

China is not alone in pursuing underwater vehicles, in a bid to get an upper hand in the open seas.

One initiative the Chinese will no doubt be aware of is the Sea Hunter -- an unmanned “sub hunter” designed by the US Navy to deal with the problem of China’s rapidly expanding fleet of submarines.

Fitted with a host of different sensors and radars, it also uses artificial intelligence to help it operate independently for months at a time. Using sound and image signatures, it can compare its target to previously identified vehicles and use that information to help it decide what to do next.

Russia has also been busy developing its own AUVs -- short for autonomous underwater vehicles. The difference? Theirs is capable of carrying a nuclear warhead.