The US military increasingly relies on drones to carry out a multitude of tasks, usually those deemed too “dull, dirty, or dangerous” for manned missions. Most unmanned aerial vehicles (UAVs) carry out routine reconnaissance. They also act as decoys, serve as communication relays, and even deliver light cargoes. But a growing number of drones are armed, such as the US Predator and MQ-9 Reaper, which are used mostly in tactical situations, such as targeting terrorists or insurgents.
Now military strategists are considering acquiring longer-range drones, especially those capable of carrying out nuclear missions. In 2015 there were reports that Russia was attempting to build nuclear-armed drone submarines.
It is a controversial strategy, given that it takes all the usual qualms there are about the increasing use of autonomous systems for war-fighting – the ethics of devolving too much authority to what are basically robots, susceptibility to hacking, etc. – but with much greater destructive power, given these systems’ range and payload. Nevertheless, it is at least worth considering.
In fact, such a strategic drone may already be in the offing. When the US decided to go ahead with a next-generation strategic bomber, the Long-Range Strike Bomber (LRS-B), the program included both manned and unmanned systems. The LRS-B, or B-21 Raider, which replaces both B-52 and B-1 bombers, is intended to carry out a broad range of missions: nuclear attack, strategic and tactical conventional strike, surveillance, intelligence, and reconnaissance (ISR), and electronic attack. Initially, the US military plans to acquire 80 to 100 LRS-Bs, but the number could eventually rise to 200 bombers.
Some of these missions probably do not require a manned system, and thus a drone version of the LRS-B could perform many of the more mundane tasks, such as ISR or electronic attack, without putting unnecessary stress on crews.
Conventional strike missions with precision-guided air-to-ground munitions is also something that could be considered for an unmanned system, as it would provide the US with the means for long-range, large-payload ground attacks. These types of missions can presently be carried out only by B-52 and B-1 bombers, which are becoming increasingly obsolete; shorter-range systems such as the F-35 Joint Strike Fighter, area very limited in their capacities for ground attack.
In such a role, an unmanned LRS-B could probably pack quite a lethal load and avoid putting a manned crew in harm’s way.
More controversial, perhaps, is the idea of an unmanned version of the LRS-B delivering nuclear weapons. Of course, the US military already operates a number of unmanned nuclear-delivery systems; they are called ballistic missiles (think of them as a single-mission, one-way drone).
Nevertheless, nuclear-armed drones still raise considerable hackles. What if such a drone could be hacked and forced to crash or be redirected to another target? How does the drone’s remote operator ensure near-total control of such a lethal weapons platform?
And nuclear drones could come in smaller packages, too. Thus far there have been limitations on the transportability by air of nuclear bombs with relatively high yields.
One of the goals of a nuclear weapons designer is to achieve the optimum yield-to-weight ratio – that is, the amount of bang per mass, usually expressed in terms of kilotons per kilogram (kt/kg). And thus far, we have needed powerful airplanes and missiles to deliver such explosive capability (compared to conventional warheads) in such relatively small amounts of weight compared to the amount of conventional warheads we would need to achieve the same destructive power.
But the technology of additive manufacturing may diminish this problem. At least in theory. Additive manufacturing – where 3-D printing machines can build objects of any shape and size by laying down successive layers of material – brings new opportunities for building much more lightweight structures.
A structure can be built with the needed strength but can be considerably lighter than a conventionally-built counterpart. One approach, for instance, is to build a lattice structure of different chemical components – either for the delivery system or the bomb casing itself, since the mass of plutonium or uranium itself cannot be modified.
More lightweight nuclear weapons present new deployment and delivery opportunities. They could be much more furtive and more difficult to detect; they could be carried by small drones and therefore be much harder to detect by enemy air defenses, since an adversary would normally be expecting a ballistic or cruise missile, or a bomber.
Longer-range drones make a lot of sense for the US military, when it comes to projecting power into the far Western Pacific. It still suffers from the centuries-old challenge of the “tyranny of distance.” It can take up to three weeks for US naval forces to steam from ports on the west coast to the South China Sea. Forces based in Hawaii could take up to 16 days to reach this area, and even Guam is a 3- to 5-day journey away. Considering this strategic straightjacket, drones make a lot of sense.