As military competition intensifies in the western Pacific between the US and China, submarines have become one of the key areas. China’s heavy investment in missiles has put at risk US land-based forces in the region and some of its surface vessels. As a result the US is investing $8 billion next year in submarines to “ensure ours is the most lethal and most advanced undersea and anti-submarine force in the world”, as Mr Carter put it last week.
Small, remotely operated subs have been used for some time in search and rescue and the Navy has been using Remus drones to search for mines. The new investments are in more autonomous vessels that might eventually carry weapons.
Last autumn, the US Navy unveiled a 10-foot, semi-autonomous sub drone known as the large displacement unmanned underwater vehicle, which is due to conduct its first test voyage in open seas in the summer. Officials hope that a squadron will be operating by 2020 if tests go well. As well as being able to operate for 30 days at a time, other distinguishing features of the submarine include being yellow.
The initial function of sub drones is expected to be surveillance, however naval planners believe there are endless potential uses. One model is what one official calls a Russian doll approach — with a mother sub or surface vessel that can then release a series of much smaller drones that could be mines or used to track subs or even launch their own missiles.
Small sub drones would be much harder to monitor using sonar systems that are designed to find large objects in deep waters. It might be possible, for instance, for a vessel to enter an enemy harbor unobserved.