The threat of a Chinese invasion of Taiwan remains one of the most pressing issues for U.S. foreign policy. Permanently deploying forces to deter or counter such an invasion would be an expensive proposition tying up a large proportion of the Pentagon’s assets. Researchers from thinktank RAND Corporation believe a new approach based on low-cost drones could do the job simply, easily and without any new technology.
The idea comes from Dr. Thomas Hamilton a Senior Physical Scientist at RAND, and David Ochmanek, a Senior International/Defense Researcher. Their paper, commissioned by the U.S.A.F.’s Warfighting Integration Capability team, is unassumingly titled Operating Low-Cost, Reusable Unmanned Aerial Vehicles in Contested Environments. Look closer and you find a blueprint for a new type of warfare.
The starting point is the need for targeting. An invasion fleet can be spotted easily enough from space, but getting precise enough information to guide missiles is another matter.
“We’ve been working on the Taiwan problem for almost twenty years with insufficient appreciation for targeting,” Ochmanek told Forbes. “There are several hundred ships you care about, but there are many hundreds of other vessels in the area – escorts, decoys, fishing boats and other confusers.”
Hamilton and Ochmanek believe that close-in reconnaissance to distinguish and pinpoint the valuable targets could best be carried out by a large number of drones, whose overlapping fields of view would cover the entire area of operations. About 500 would be enough for a ‘mesh’ able to see and precisely locate every ship from multiple angles.
“The object of a targeting mesh it to be able guide a missile on to a specific ship – and if it’s a big ship, guide it to hit the engine room.” Says Hamilton.
The researchers looked at the current low-cost attritable aircraft technology (L-CAAT), typified by the XQ-58 Valkyrie developed for the U.S. Air Force. This 6,000-pound drone is bigger than needed to carry the necessary sensors, so they looked at a scaled-down 600-pound version they dubbed the Kitten.
“We buy aircraft by the pound, and a 600-pound aircraft costs about a tenth as much as a 6,000-pound one,” says Ochmanek. “And for this mission you want it to be inexpensive.”
The Kitten will have a small jet engine, a wingspan of about eighteen feet, and will cruise at around 560 mph for six hours. The researchers estimate, based on discussion with suppliers, that each Kitten will cost around $300,000.
The Kittens will have comparatively simple sensors based on commercial technology. Rather than trying to observe from long range, they would get as close as they need to.
“The concept is that when you see something and you’re not sure of what it is, you mass and send several Kittens in for a closer look,” says Ochmanek.
Communication within the mesh, and with remote human operators using several hops, is provided by millimeter-wave (MMW) radio, a technology already widely used for 5G communications.
“We noticed the cellphone industry had developed the technology,” says Ochmanek. “They have already invested billions of dollars, and we leverage off this.”
MMW radio gives high bandwidth but short range. It allows adjacent drones to communicate with each other, relaying signals to and from the human operators. The short range is not an issue because members of the mesh are packed close together. And because MMW signals do not travel far, it makes long-range jamming impossible, as the jamming signal is blocked by a few miles of air.
“For us, the short range is not a bug but a feature,” says Ochmanek.
The real threat to the mesh will not be jamming but Chinese surface-to-air missiles. The invasion fleet will unleash a massive barrage of guided missiles at anything which looks like an enemy aircraft. For example, each Type 055 destroyer has 128 launch tubes, many of which will be loaded with surface-to-air weapons, and there will be many such escorts.
Rather than protecting the drones with jammers, stealth or other defensive aids, the plan is simply to saturate the defenses with drones, eventually exhausting the enemy’s supply of missiles. Like the supposedly unkillable Immortals of ancient Persia, the targeting mesh maintains its strength by continual replenishment, with each casualty being immediately replaced with a fresh drone.
“We made some conservative assumptions, and, giving the enemy credit for a frictionless air defense, we believe they may be able to fire on the order of several thousand missiles,” says Hamilton. “So we might have to put up several thousand Kittens in a short space of time to maintain the targeting mesh.”
So instead of five hundred drones, the scheme actually requires thousands — but affordable drone design makes the scheme feasible. At $300k a time, the drones will be cheaper than the missiles fired at them; the U.S. Navy’s own Standard-6 anti-aircraft missiles cost over $4m a shot.
Faced with an enemy which simply absorbs all its missiles, the Chinese may prefer to conserve their ammunition for more important targets like manned aircraft and incoming cruise missiles. Whether they would have the nerves to simply ignore multiple drones closing with their vessels at over 500 mph is another matter. In any case the mesh is an effective missile sponge, diverting anti-aircraft fire away from piloted aircraft.
As the mesh is so difficult to kill in the air, the Chinese might want to take out the drone launch sites. But, based on experience from previous exercises, the researchers have taken an approach which avoids using conventional airfields.
“In all of our wargaming, the allied team confronts problems sustaining sortie rates from fixed airbases,” says Hamilton.
Mobile units, each of which consists of little more than trucks and trailers, would launch the drones. Similar mobile launchers have been used for unmanned aircraft operations since the 1960s, and have proven practical and rugged. Such units are hard to find and identify from the air, and the dispersed approach poses the Chinese the same challenge that proved so difficult for Scud-hunters in the 1991 Iraq war.
Even if the launchers could be found, they would be unlikely to attract the same sort of counter-force strikes as airfields.
“There just a few people and trucks there, nothing worth the cost of a TBM [Tactical Ballistic Missile],” says Ochmanek.
The RAND team calculate that one squadron of 500 personnel could launch 1,200 Kittens in a 24-hour period. Five such squadrons would be enough to cover the entire Taiwan invasion area with a dense targeting mesh.
So how much difference could the mesh of unarmed drones make to an invasion?
An astonishing difference, thanks to the under-appreciated benefits of precise targeting data.
The researchers estimate that there will be around 1,550 ships in an invasion force in the Taiwan Strait: 50 high-value ships, amphibious vessels carrying at least 50 tanks or equivalent each, 250 repurposed commercial vessels carrying ten tanks each, 250 more commercial vessels with 4 tanks, and 1,000 other ships that play no direct role in the invasion and which are considered decoys. The exact numbers are not as important as the ratio of valuable targets to low-value and decoys targets which would waste allied missiles.
Without effective targeting, the study shows it would take some 10,000 AGM-84 Harpoon missiles to knock out 72% of such a fleet’s tank-carrying capacity. With the targeting mesh though, just 1,000 weapons can destroy ‘upwards of 80%’ of the invading tanks before they can land and bring the invasion to a grinding halt.
These numbers are highly significant. Massing 10,000 Harpoons would be virtually impossible, but 1,000 is more than feasible. The most effective delivery platform would be Virginia-class nuclear attack submarines: the latest extended version can carry 65 missiles each. The Navy plans to have 31 Virginia Class subs with the extended missile fit. In other words, in principle the Navy could do the job with a fraction of its submarine fleet. (Targeting data might also be passed to allied submarines such as those being acquired by Australia or operated the UK also in the new AUKUS alliance).
Finding a ship target at long range can be a challenge for a submarine, especially if it is sailing with a mass of other vessels. This is exactly the problem that the targeting mesh solves so neatly, ensuring that every shot counts while the submarines remain a same distance from ant-submarine forces.
Submarines could be supplemented with other launch platforms such as ships or even long-range aircraft. A B-52 bomber can carry 8 to 12 Harpoons. In principle a hundred B-52 sorties could deliver all the firepower necessary to take out the invasion force, again while staying back from defenses – with a little help from the targeting mesh.
Hamilton and Ochmanek’s paper was well-received, and was followed by another, more detailed study which has not been made public.
“We’ve taken technical analysis on paper as far as we can,” says Ochmanek. “It looks feasible but until you use it in air vehicles, it’s a bit hypothetical.”
The next stage would be experimentation and demonstrations with air vehicles, testing out whether the sensors, communications and launch proposals would work out as planned. The researchers were not able to discuss planned funding or development of such work.
For some, the ever-replenished drone targeting mesh will looks like a crazy idea. But others will find it appealing on many levels. For one thing, it is a true force multiplier, magnifying the power of existing assets rather than replacing them. It is a low-risk option, as it does not rely on new technology. The researchers note that emerging capabilities like drone-based AI would benefit the mesh, but are a bonus rather than a requirement.
Mainly though, the targeting mesh comes with a strikingly low cost: the complete supply of drones, launchers and the personnel to handle them would be could be put in place for a fraction of the multibillion dollar price tag for a single new destroyer or submarine.
The targeting mesh is not quite a drone swarm, as the drones are not autonomously co—operating as a group. But it gives an idea of just how powerful large numbers of inexpensive drones can be when used with some imagination. And the very existence of a targeting mesh might be enough to persuade Chinese planners that an invasion of Taiwan is impossible, making it an effective and affordable non-nuclear deterrent.