A research team in China has unveiled an underwater drone that can recognise, follow and attack an enemy submarine without human instruction. The secret project, funded by the military , was partially declassified last week with the publication of a paper that gave a rare glimpse into a field test of the unmanned underwater vehicle (UUV), seemingly in the Taiwan Strait, more than a decade ago. How 23 giant Chinese rockets could save world from asteroids It is unclear why China has now declassified details of the test, but the tension over the Taiwan Strait has recently escalated to its highest point in decades. Countries such as the United States and Japan have raised the possibility of military intervention if Beijing, which views Taiwan as part of its territory, tries to take the island by force. These robotic drones are now working mostly individually, but with technological upgrades could patrol in packs, according to Professor Liang Guolong and colleagues from Harbin Engineering University, China’s top submarine research institute. A variant of the sub could be planted on sea floors and activated in the event of a clash or war. “The needs of future underwater warfare bring new development opportunities for unmanned platforms,” the researchers said in their paper, published in the Journal of Harbin Engineering University last Friday. Most submarines have computers to help identify or track targets, but sonar operators still need to use their eyes and ears to make judgments on important issues such as identifying friendly vessels, with final decisions taken by the captain. The external environment’s complexity means humans normally “need to fine-tune the sonar from time to time to improve the results of searching and tracking”, Liang wrote. On the unmanned submarine, “all the subsystems such as information acquisition, target detection, assessment, status and parameter control must have completely independent decision-making capabilities”, rendering some traditional submarine technology “useless to an unmanned platform”, he said in the paper. Although the researchers did not give a precise location, partial coordinates from a map in their paper suggested that they dropped an unmanned submarine off the coast of the eastern province of Fujian, in or near the Taiwan Strait. The drone was programmed to patrol about 10 metres below the surface following a predetermined route. At another location, the researchers deployed a mock craft that could replicate the noise of a submarine, and the drone switched to combat mode as soon as its sonars picked up the signal from distance. It circled in a hexagonal pattern and pointed its sonar arrays to various sources of sound, while artificial intelligence tried to filter out ambient noise and determine the nature of the target, according to the researchers. One torpedo fired by the drone hit the simulated submarine. For safety reasons, the torpedo was not loaded. That test, conducted in 2010, was China’s first attempt to simulate the tracking and sinking of a submarine “with the complete absence of humans in an open environment”, Liang and colleagues wrote in the paper. Unmanned submarines could make mistakes, and their communication with human commanders could be interrupted by enemies. Whether a robotic killer should be let loose to hunt and kill humans remains an ethical question. South China Sea: the dispute that could start a military conflict Nonetheless, the US military has asked Boeing to build four extra-large Orca UUVs, and Russia recently deployed a new submarine that can launch a nuclear-powered drone with enough firepower to wipe out cities. Israel and Singapore, among others, have tested or deployed similar machines in the oceans, according to Liang. China’s unmanned submarine project started in the early 1990s, long before AI became a buzzword. Although there is no recorded use of them in a real battle, China’s unmanned subs have since evolved, incorporating improvements in sonar technology, AI and communications to allow them to coordinate their movements as a fleet and launch attacks on the same target from different positions simultaneously, Liang wrote, adding that with a new-generation power supply, they could hide for long periods to ambush enemies. The drone is part of a wider effort by China to challenge other nations’ dominance in the world’s oceans with disruptive AI technology. Chinese unmanned platforms deployed or under construction include surface vessels, long-distance gliders that can cross an ocean to gather information, a research station on the deep sea floor of the South China Sea , and a UFO-like drone that can both fly and cruise under water.