The Compelling Case For Arming U.S. Navy Warships With Drone Swarms

In and around the Red Sea, the constant Houthi aerial drone attacks on ships, including U.S. and allied surface combatants, have made major headlines. Near Ukraine, we have seen repeated successful attacks on Russian warships via unmanned surface vessels. The use of relatively inexpensive unmanned systems in a maritime context is typically viewed through the lens of them being threats to warships. However, the potential for lower-end drones to be used to those same warships' advantages, both defensively and offensively, is arguably just as big of a deal.

Yet few are talking about it, especially when it comes to using crewed vessels rather than the possibility of uncrewed ones as hosts sometime in the future.

With very limited extra space available and no current way to reload vertical launch system (VLS) cells at sea, the mix of weaponry and the size of the magazines aboard America's surface combatants, both present and future, are being deeply evaluated. You can read all about this issue in our recent feature here. While adding more large, very expensive, and complex missiles would be nice, that may not be possible to do with any efficiency. On the other hand, adding magazines filled with much smaller and cheaper aerial drones is far more feasible, and doing so can vastly increase the combat flexibility and overall capabilities of an advanced warship.

One could even make the case that, at least in some ways, up-arming surface combatants with magazines full of drones has become as relevant as shoehorning in more missiles. What I am talking about here is giving America's surface combatants the ability to rapidly launch everything from a single drone to swarms of low-cost, but highly adaptable, drones that can reach out hundreds of miles and stay airborne for hours at a time. In many cases, they can also be recovered and reused.

As noted in the introduction, multiple real-world events are giving U.S. Navy planners a lot to think about as of late. The war in Ukraine, and especially the use of unmanned surface vessels in that conflict, as well as a potential looming fight across the vast Pacific with China, are two of them. However, the ongoing crisis off Yemen's shores that has seen commercial and military vessels repeatedly attacked using drones and cruise missiles, as well as the first use of anti-ship ballistic missiles, is perhaps most concerning. This is a far more geographically compact, lower-end threat than what the U.S. Navy would experience in the Pacific against China. As of mid-February, American surface combatants had fired well over 100 Standard Series (SM-2 and SM-6) missiles, and likely other types on top of that figure, at Houthi threats. That number is markedly larger now. Even replenishing these weapons is becoming a budgetary and procurement challenge.

Lower-end one-way attack drones cost a fraction of a missile, but can still pose a major danger to warships. They can also suck up precious interceptors fired from those ships in defense. On the other hand, if a U.S. Navy ship wants to hit a small target at long range, and especially in a contested area, its only choices currently are launching a BGM-109 Tomahawk cruise missile or an SM-6, with the Naval Strike Missile also now emerging as an option on some vessels. All these missiles cost over a million dollars each, and most cost multiple millions of dollars, and are limited in quantity. The same missiles (albeit only certain variants of the Tomahawk) can also prosecute maritime targets, along with the RGM-84 Harpoon, although the latter has relatively limited range in comparison. Adding long-range loitering attack munitions to a ship's arsenal can completely change this equation.

Outside of kinetic roles, lower-end drones launched from warships also can provide general intelligence, surveillance, and reconnaissance (ISR) applications that could be used every day, significantly expanding the aperture of the ship's situational awareness. Everything from search and rescue operations, surveilling ships for sea control purposes, collecting electronic intelligence near an enemy coastline, supporting special operations inland, as well as responding to natural disasters could be done with great efficiency by these systems. This would be without having to launch, in the U.S. Navy's case, the MH-60R Seahawk helicopters from ships, and possibly putting crew members at risk, or using much more advanced and costly drones. Otherwise, these smaller drones could augment the Seahawks and even allow their crews to control their movements. Just scouting ahead of the ship, especially in areas where force protection is a major issue, would be valuable. Above all else, many drones can be in many places at one time. A helicopter can only be in one.

In addition, adding scores of smaller long-range drones to surface combatants can also add significantly to their defensive, communications, and electronic warfare capabilities, as well.

With that introduction behind us, now let's get into the details.

America's surface combatants are tightly packed without much room for new large weaponry. Some are even growing to almost comical proportions as they approach the mid-life points in their service in order to pack in more capabilities. Vertical launch system (VLS) arrays are extremely prized real estate aboard the U.S. Navy's Arleigh Burke class destroyers and Ticonderoga class cruisers, as well as the three-ship Zumwalt class of stealthy destroyers and the upcoming Constellation class frigates. Once again, you can read about this issue in great depth in our previous feature linked here. Suffice it to say that adding more large weaponry isn't going to come in the form of additional traditional VLS cells on the Navy's existing surface combatant fleet. Bolting on deck-mounted angled box launchers is a possibility, but these take up a lot of deck space and add weight for very few extra missiles. It could still possibly be a worthwhile endeavor, but doing so has a limited return.

Expendable (or optionally expendable) drones with hundreds of miles of range and long loitering capabilities already exist and many use a Common Launch Tube (CLT) or a similar system that can be slapped on just about anything — from buggies to helicopters to advanced drones. These tubes can hold different types of drones or examples of a single type outfitted for different missions — some carrying a warhead, some an electro-optical payload, some electronic warfare capabilities, while others could carry electronic surveillance or communications relay systems. Drones with these myriad configurations can have their launch tubes packed tightly together into armored boxes to create their own mini-VLS arrays. Instead of penetrating down many levels and taking up huge parts of the ship's topside, these boxes could be installed virtually anywhere with available space, and in any size or shape.

This means an American destroyer could be rapidly equipped with dozens of drones at the ready, capable of multiple missions, without a refit or huge expenditure. These 'bolt-on' additions can go where there is room and don't need to all be clustered together in one weapons 'farm' or 'array.'

For instance, a box of 12 drones could go on the bow, another box of 24 can go in an open spot behind a vertical launch system array, and two boxes of 36 drones can be placed on each side of the superstructure amidships. Smaller boxes of less than a dozen drones could even be hung off the ship's superstructure. The configuration possibilities are really expansive. It could be a totally scalable concept that could grow and evolve over time. Alternatively, extra drones packed into standardized launch tubes as individual 'rounds' could be stored inside the ship's armory and reloaded as needed by the crew, so fewer drones at the ready would be needed. Even a single box, or pair of boxes, and additional pre-loaded tubes in storage could handle most tasks, including launching swarms on demand. Larger swarms could be launched beyond what's at the ready with more sent on their way after reloading the box launchers.

The drones in their launch tubes could also be packed in large quantities inside a customized shipping-like container and placed aboard any ship, for added flexibility. This could offer U.S. Navy support ships an aerial multi-role standoff capability. Yet having them installed and ready to go on major surface combatants, so they can be integrated into all the ship's other capabilities — where they could even help defend the vessel — would be very advantageous. Still, a modular concept could make any ship with enough deck space a 'shooter' and a multi-role aerial capability mothership.

Taking an off-the-shelf drone system like the Altius 600, which can fly for four hours and reach roughly 275 miles, makes perfect sense. The cost will only drop as more are being procured by various services and new Altius variants are being developed, some with much longer range and others that are further payload optimized, such as the hard-hitting, but shorter-ranged Altius 700M.

The drones in the Altius family are just some examples of an increasingly diverse marketplace for similar capabilities, with offerings from many manufacturers, including established firms such as Raytheon (RTX) and AeroVironment. The nice thing about the armored box launcher concept — where, essentially, a lid pops open and the drones are launched vertically from their replaceable tubes — is that different types from different manufacturers, and even ones that use different tube diameters, can be added easily as new capabilities with specific attributes are needed. In other words, mixing and matching drone types within the array would be relatively simple and this would create high competition in an already rapidly expanding market space.

A possible alternative to a box launcher would be using the VLS cells themselves to launch small drones. Just as a thought exercise, assuming this is achievable, a strike-length Mk 41 VLS cell is 25 feet long, so eight three-foot-long drones could be packed into that length, although that number would be less with the addition of some sort of small boosters (or compressed air system) and separation plates. Let's call it six vertically. Still, considering you could at least quad-pack each cell just as the Evolved Sea Sparrow Missile currently does, that would mean each cell could theoretically hold 24 drones. That is an immense amount of capability for a single VLS cell. Just four of the Arleigh Burke Flight II's 96 cells could pack nearly 100 drones using such an arrangement.

At the same time, this would take away valuable cells from much larger and more capable weapons, and servicing or replacing the drones would be more problematic using this arrangement compared to a simple box launcher. Malfunctions with one drone in a stack could also keep the rest from launching. On the other hand, packing small drones vertically into a VLS cell is a very intriguing idea that would require modification only to the inner cell/canister itself and may be attractive for international users which already have VLS arrays installed. The drones could be added as needed with the cell taking on a normal missile payload instead without issue.

Once again, drones could be used for strike, surveillance, stand-in electronic attack, and communications relay missions, as well as serve as decoys. Types optimized for low speed could even create phantom fleets for hours at a time, something the Navy is already highly interested in developing. The communications relay part is important because using one drone as an airborne relay means that other drones can retain direct connectivity with the ship over long distances without using a more exquisite airborne relay platform or satellite communications, both of which could become vulnerable to attack. Multiple relay drones can also be strung out or 'daisy chained' over longer distances to maintain connectivity with drones and other systems that are farther down range. This would be especially critical for search and destroy, and surveillance, missions. Multiple communications relay drones, or even drones with more basic communications packages, can create mesh networks over great distances. Otherwise, the drones can be used in 'fire and forget' modes for certain roles, like attacking fixed targets or acting as decoys, and even some surveillance tasks where real-time intelligence products are not necessary and the drones can be recovered after their sorties. Once back onboard a ship, the information gathered would be downloaded.

If infused with a high degree of autonomy, which could allow them to choose their own targets under certain circumstances, these drones can be far more flexible and effective even without a direct command link. Allowing them to search and investigate targets of interest on their own in predetermined areas wouldn't be a 'moral' issue, but executing their own attacks would be another story. I think it's very likely this will become a necessary capability as foes will have no such concerns with deploying it. You can read all about this and the issues surrounding autonomy and the next leap in lower-end drone warfare in this past feature of ours.

When you layer in these different capabilities, where some drones can hunt and some can kill, and others can provide communications facilitations, while others jam and decoy enemy air defenses, you can see just how scalable and potentially impactful these lowly ship-launched drones can be. This is all without cooperative swarming. Once that is included — where the drones can communicate and coordinate operations with each other with some autonomy and react dynamically to their environment — we are talking about a whole other level of unmanned warfare, which is certainly coming fast.

A surface combatant could put up its own swarm of drones that creates a mesh network capable of cooperatively searching broad areas of the ocean for things like enemy ships and submarines or a downed aircrew. Then this information can be passed back to the ship in real time and from there the data can be sent around the battlespace and even the globe. In the case of finding an enemy target, it could then be decided to attack it using a drone that is part of the swarm, or by launching a weapon from the ship, or another platform in theater. This drastically expands the scope of the kill chain and speeds it up.

The swarm is also resilient. If some drones are lost, the swarm will optimize automatically to make the most out of the capabilities still in play. With a higher level of autonomy, a corporative swarm can confuse, overwhelm, and break an enemy's decision-making cycle, overcoming their defenses in multiple ways before the enemy can fully react.

A mesh-networked, highly resilient swarm operating over a broad area will be absolutely critical to succeeding in future fights. You can read just how big a factor this has become in war gaming, in this case in a potential cross-Taiwan Strait conflict, here. Giving American warships, which would already be deployed far forward, the ability to unleash such swarms, and tailoring them to the mission at hand, would be a massive advantage and force multiplier not just for the ship, but for other friendly assets in the battlespace that are exchanging information.

When it comes to kinetic striking capability, these small drones could be very problematic for enemy surface combatants, even large ones. While they are unlikely to sink a ship or even damage it beyond repair when employed in small numbers, they can easily cause a mission kill by damaging the ship's critical sensors, communications, and engineering components, as well as preoccupying its crew with damage control measures. In the long term, this could put the ship out of action for an extensive amount of time, effectively taking it off the board. In the short term, such an attack could leave the same ship in a wounded state, very vulnerable to follow-up attacks by more sophisticated weapons with its defenses degraded.

When used in large numbers, these drones, cooperatively swarming or not, can deplete a ship's defensive arsenal, attacking from multiple vectors. Close-in weapon systems can quickly run out of ammunition and need reloading, leaving the ship's inner point defense layer degraded and thus making the vessel more vulnerable. Even American and allied warships facing off against the Houthi drones have had to use close-in weapon systems to take them down.

Now, sending a flock after a ship, with many dozens of drones to defend against, could quickly become an impossible task, with the ship's defenses rapidly becoming overwhelmed and its magazines running dry. Considering the quantities involved, a ship may be able to readily defend itself against a limited number of drones, but many attacking at the same time from different vectors would be a different story, especially as some of the drones could be used as electronic warfare platforms and decoys, further challenging a ship's defenses.

A single $2 million Naval Strike Missile can be defeated with a single missile or even a decoy, but doing the same to 40 drones with the same total price tag would be a much tougher proposition, especially when they can be programmed specifically to attack in a manner as to exploit weaknesses in a ship's defensive capabilities. Add in a swarm component, where the drones are working together autonomously in real-time, and defending against them only gets tougher.

When an anti-ship swarm is used in conjunction with a layered attack, where cruise missiles and even ballistic missile-like attacks from SM-6s are feathered in, it could pose a massive problem for not just one of the most advanced enemy warships, but an entire flotilla. In other words, drones can provide combat mass — a dynamic quantity problem that must be dealt with — allowing more advanced weapons to have an even greater impact.

So yes, we are talking about a very troublesome capability that is still chronically underestimated. Warships are far better equipped to deal with advanced anti-ship cruise missiles than a swarm of relatively small drones.

Working to counter small boat attacks is also a key capability that a ship's magazine of aerial drones can offer. They can loiter for hours in the vicinity of the ship and rapidly identify and strike any approaching hostile surface threat with pinpoint accuracy. Their control could be integrated into the Aegis Combat System to best allocate their attacks based on the most pressing threats. Some Navy Littoral Combat Ships are being equipped with vertical launch AGM-114 Hellfire missiles for counter-small boat operations, which are far less flexible and have much shorter ranges than the drones we are discussing here. Some of the drones could even be fitted with similar millimeter wave-radar seekers as the Hellfires use for this application, with target assignments data-linked to them in real-time.

The space taken up by Hellfires on some LCSs would be far better utilized as a multi-mission drone launch farm, but the defense of a ship from small manned and unmanned surface threats via loitering munition drones is in no way specific to the LCS. These drones' long endurance and ability to carry both electro-optical and warhead payloads can allow them to respond to small boat threats far out from the inner defensive bubble around a ship.

Finally, these smaller drones can work to defend against similar lower-end aerial drones by hunting them down and killing them kinetically or via non-kinetic electronic attacks. As we made the case for doing long ago, the best defense against drones, at least in some cases, is other drones. These capabilities now exist at various performance levels. It's even possible a preemptive counter-drone screen — like a drone combat air patrol — can be put up a significant distance from the ship that can work as a layer of defense against both aerial and surface drone attacks.

Understanding what small surface and aerial threats exist beyond a ship's radar horizon is a challenge. Sending out drones to search for hours beyond this horizon would allow for early warning of such threats in high-risk areas, and they could even stop them long before they pose a major threat to the ship. A single drone type could both hunt for and, if need be, kill such a target. For countering surface threats, while an MH-60R Seahawk can only be in one place at one time, a number of drones can be launched to cover multiple relevant potential vectors of potential small boat attacks, and persist in those areas far longer than a Seahawk could. The same sort of application can be used for countering aerial drones, where they could be sent a distance from the ship and could be ordered to intercept threatening drones on demand.

Higher-performance jet-powered anti-drone drones, like Raytheon's Coyote Block II or Anduril's new Roadrunner, are specifically designed to make faster intercepts of drones, including swarms. In the case of Coyote Block II, they have been successful in doing so. It's possible that these same drones could share launcher boxes with lower-performance, propeller-powered types. There are propeller-driven counter-drone configured drones, as well, for lower-performing threats that can be launched from CLTs and other similar systems. Any of these types, jet or propeller-powered, can also be equipped with electronic warfare payloads capable of 'soft kills' against drones, allowing a single drone to take down multiple threats.

The bottom line here is that counter-drone drones could drastically help U.S. Navy ships reliably take down threatening drones without spending millions of dollars on an interceptor or letting the drone get so close to the ship that gun systems need to be employed. The Navy is now racing to fill just such a gap, which these systems seem ideally suited to do.

Compelling capabilities are now baked into readily available lower-end drones that can fulfill many missions and solve many tactical problems at a comparatively very low cost for U.S. and allied warships. Beyond that, with the sheer combat mass they can provide and their collective overmatch capabilities that are now cresting the horizon, it's extremely puzzling why fielding them as fast as possible is not a bigger initiative for the U.S. Navy.

It absolutely should be.

While multi-million dollar missiles are critical to the fight, giving American warships an array of lower-end standoff capabilities via small drones, and eventually the ability to deploy large cooperative swarms, will become just as important in many regards as those multi-million dollar missiles, whether the Navy likes it or not.

What are we waiting for?

Contact the author: tyler@twz.com