Source: https://chinaplus.cri.cn/news/china/9/20170611/6177.html

The spectacular success of drones of all shapes and sizes in the ongoing Russia – Ukraine conflict, and their use by the Houthis show the limitless potential of drones as weapons of war. Drones can be either operator-controlled, semi-autonomous or autonomous. Each method of control has its pros and cons. While the larger military grade drones launched from land or from sea can be destroyed by existing weapon systems on board warships, it is the smaller sized drones that pose a new challenge to warships. In this article, we will restrict the scope to the use of small drones for warfare at sea.

Drones can typically be classified as Unmanned Aerial Vehicles (UAVs), Unmanned Surface Vessels (USVs) or Unmanned Underwater Vehicles (UUVs). Within this broad categorization is an alphabet soup of subclassifications that only serve to confuse and we shall not delve into each subtype.

From the Naval Operations point of view, drones  can be used for the following purposes:

•             Surveillance

•             Communications

•             Transportation

•             Combat

Sea warfare has certain peculiarities unlike land warfare. Firstly, there are no mountains, ridges, or terrain on the surface to hide behind. Detection of any aerial object at sea is far simpler as compared to aerial objects over land. Vessels plying on the surface can be detected at reasonable ranges for countermeasures to be effective. The real danger lies when the attacking vessel is partly submerged or underwater. Then the advantage shifts to the attacker.

Aerial drones launched from ships suffer the same disadvantages as any aircraft operating from ships. They are maintenance intensive. Sea spray is so corrosive that after every use, aircraft have to be washed down thoroughly. Rotating machinery is especially susceptible to damage from corrosion and build-up of deposits. So, all DJI variety quadcopters are likely to have an extremely short life out at sea.

The biggest limitation of any drone is the power source. Since the adversarial forces at sea are likely to operate at extended ranges, what works on land like the First-Person View quadcopters chasing and killing individual soldiers or hitting armoured personnel carriers will not work at sea. The likelihood of any such drone approaching a warship at sea unhindered is most unlikely.

The situation changes in restricted waters or close coast operations. In that case, such drones can be of some use. The reason is that most naval sensors and weapons of major warships are designed to operate at extended ranges away from land clutter. Hence when operating in close proximity to land, small flying objects may not get detected unless the sensors are either designed for close coast operations or the existing sensors are tuned to operate close coast in which case their long-range detection capabilities suffer. Sensors that can combine both are expensive and difficult to maintain.

Soft kill measures such as GPS or Communication jamming may or may not work. With the advent of AI-programmed autonomous drones(1) soft kill measures will increasingly become more difficult.   A small quadcopter or fixed-wing drone whether launched singly or in a swarm with just 25 grams of explosive content has to just target a warship’s radar antennae or go down the engine exhaust funnel to seriously degrade combat capability.

New-fangled hard kill measures such as laser weapons are prohibitively expensive(2) and have major limitations due to the underlying physics and inclement weather (3). Pure waste of good money.

The other alternative is to sanitise the surrounding land mass and neutralise the operators which may prove to be resource intensive. In such cases what practically can work while leaving harbours or operating close to land is a good all-round visual lookout and personnel armed with weapons that have large spread patterns such as a shotgun loaded with bird shot. Investing in gyro-stabilised optronic Close in Weapon Systems (CIWS) with high spread patterns for point defence against drone swarms is the way forward.

The significant success of Ukrainian Unmanned Surface Vessels (USVs) against the Russian Navy in the ongoing conflict again shows that navies are ill-equipped to counter this form of threat. Warships at anchor or alongside are particularly vulnerable against a fast-moving low freeboard target that is difficult to hit. Here again, the choice rests between neutralising the operators which is difficult or hard kill measures which are also difficult. In harbours or at anchorage, the best counter to USVs is a combination of CIWS and good old Second World War boom nets. Tactical methods such as armed helicopter patrols can augment the defensive perimeter. A swarm of defensive USVs deployed around a formation of warships or a high-value warship is another expensive alternative.

The toughest threat to counter would be the Unmanned Underwater Vehicles (UUVs) that can either approach underwater or pop up like the latest Chinese underwater-to-air drone called Nezha (4). Underwater drones need not carry a large explosive charge to cause significant damage. Just chipping a warship’s propellers is sufficient to put her out of action. Nature truly is on the side of the underwater assailants. In this case too, defensive boom nets and tactical use of sonars and depth charges can be attempted. The best countermeasure of course is being mobile at high speed. Now that might sound foolish that warships are fleeing from such a small puny weapon. Unfortunately, in this case, size does not matter. Sea warriors may want to recast their concepts of warfighting. 

The threat of drone swarms launched from merchant ships is yet another possibility. A large-sized mother ship can carry thousands of combat drones and that makes every merchant ship a potential target.

In a 1991 book by Orson Scott Card titled Ender’s Game and its 2013 Hollywood adaptation, Earth utilises children to control swarms of drones to defeat an alien invasion. The logic is that children have better reflexes, imagination, creativity and lesser inhibitions to pull the trigger especially when it looks like they are playing a video game. What stops an inimical adversary from employing children on large merchant ships launching drone swarms? How do you prosecute operators aged say 12 in case they are swarm drone operators? The present international consensus on the issue of child soldiers remains undecided (5).

Now this may sound like wild thinking but the very fact that the author, a retired admiral can think along these lines means there could be many others who would be exploring the pros and cons of this course of action because the technology now exists. Not only does this possibility apply to drone warfare at sea but also to drone warfare on land.  While identification of whether a merchant ship is a Friend or a foe will always be challenging, tacticians will have to factor such a threat into their war plans.

As the threat at sea keeps evolving, navies will have to think creatively to come up with suitable counters. Not all navies can afford USD 200 Million laser weapons, Billion-dollar satellite networks and surveillance networks. Those with modest means will have to look at practical options and the same have been outlined in this article.