The Expeditionary Logistics Challenge: The Contribution of Maritime Autonomous Systems

Over 2,500 years ago, Sun Tzu noted, “The line between disorder and order lies in logistics.” While logistics may not stir a great deal of passion among warfighters, one doesn’t need to be a historian to understand the importance of logistics to warfare over many millennia. From Alexander the Great, who noted, “My logisticians are a humorless lot. They know if my campaign fails, they are the first ones I will slay,” to Captain Alfred Thayer Mahan, who said, “Logistics are as vital to military success as daily food is to daily work,” to General Robert Barrow, then-Commandant of the U.S. Marine Corps, who coined a phrase that is still a staple of war college curricula, “Amateurs talk about tactics, but professionals study logistics.” Clearly, successful military leaders know the value of logistics.

Russia’s unprovoked invasion of Ukraine, and the grinding war that has followed, will be studied in war colleges for years, perhaps even decades. Among the many lessons learned during this conflict, one that will likely be most prominent is the vital importance of logistics in warfare. The defense and open media have been filled with stories regarding Russia’s logistics challenges. One article had this headline: “Logistics Woes Hinder Russia’s Military.”

A term that has gained traction in military circles worldwide is “contested logistics.” While logistics resupply in a benign environment is hardly more difficult than logistics delivery in the commercial world, against a determined adversary possessing even modest anti-access/area denial (A2/AD) capabilities, delivering logistical sustainment is fraught with often unacceptable danger.

Logistics is a function important to all militaries, as well as to all disciplines within each military. The discussions and examples I will use will focus on naval logistics for one primary reason. Unlike armies that travel on land and who can be resupplied by train, wheeled vehicles or by air, naval forces, especially those delivering troops to a hostile shore, must bring everything they need via ships, and then move supplies from those ships to troops on the beach.

My experience and background is with the U.S. Navy and Marine Corps. I have had three tours with our expeditionary assault forces, so I am well-versed in the challenges of ship-to-shore logistics supply of Marines who have established a beach head in a contested environment and who now need more ammunition, fuel, food and other supplies to move inland to the objective area. This is one of the most challenging missions in warfare.

Armed with the experience of two-decades of war in Iraq and Afghanistan, the U.S. military is focusing more intently on logistics than it has in some time. This includes maritime logistics, a subject that has been addressed in a number of articles in professional journals. Here is how one active-duty naval officer put it in the pages of the U.S. Naval Institute Proceedings:

The great diversity of challenges that threaten the U.S. Navy in the near term – spanning all domains and all levels of warfare – has led to an unequal concentration of effort, leaving some areas unaddressed. Maritime logistics ranks chief among them…Great maritime powers have always sought the capacity to interdict their enemies “vital lines of communication” while protecting their own.

The defense website, Second Line of Defense, has featured several articles focused on logistics and the supply chain. The majority of these have focused on big picture logistics issues, for example, Robbin Laird’s, “The US Logistics Systems: The Challenge of a Strategic Reset.” SLD has also featured articles about expeditionary operations, especially those conducted by the U.S. Navy-Marine Corps team, such as, “Presence, Economy of Force and Scalability: The New Amphibious Task Force.”

Expeditionary operations represent perhaps the one area where logistics cannot be allowed to fail, or even falter. Once the landing is underway and the Marines are on the beach, if their logistics breaks down, they have few options to continue the fight, and might even have to withdraw. For all nations and their expeditionary forces, contested logistics is—and will—remain a daunting challenge. There is much that can be learned from the U.S. Navy and Marine Corps efforts to address this issue by leveraging emerging technology.

The Expeditionary Logistics Challenge

One doesn’t need to be a Clausewitz or Sun Tzu to understand the importance of logistics to warfare over many millennia, and especially to appreciate the profound difficulty of assaulting a heavily defended beach. While the Navy and Marine Corps honed this skill during World War II and have advanced this discipline over the ensuing eight decades, expeditionary assault remains one of the most challenging missions in naval warfare.

The ability to rapidly and reliably resupply Marines on the beach throughout the assault will most often spell the difference between success and failure. For Marines in the 21st Century fight, Fleet Admiral Ernest King’s strategic retrospective still applies: “It is no easy matter in a global war to have the right materials in the right place at the right time in the right quantities.”

Marines in the fight use enormous quantities of fuel, food, ammunition and other material as they attempt to move off the beachhead. While many functions are important in an expeditionary operation, once the assault is underway and Marines are on the beach, sustainment is crucial in ensuring their success. The mission will ultimately fail if the Marines are not able to have reliable and continuous sustainment to press the fight off the beaches and inland.

Marine Corps professionals have highlighted the importance of providing rapid and reliable sustainment as a critical factor in supporting Expeditionary Advanced Base Operations (EABO), with one officer, quoting the then-Commandant of the Marine Corps, General David Berger’s, Commandant’s Planning Guidance noting:

The Navy and Marine Corps will need improved logistics capabilities: We must reimagine our amphibious ship capabilities, prepositioning, and expeditionary logistics so they are more survivable, at less risk of catastrophic loss, and agile in their employment.

This article goes on to point out that traditional methods of resupplying Marines on the beach will not work, especially against a peer adversary like China which has substantial A2/AD systems that pose a serious risk for existing Navy and Marine Corps logistics platforms. Other articles have pointed out that EABO is vitally dependent on reliable logistics resupply, noting:

The inherent risk in EABO is that traditional maritime logistics will be unable to support and sustain these groups in the contested environment. U.S. forces may not have access to stocks and supplies prepositioned in other nations. Unfortunately, EABO concepts only exacerbate this long-standing problem. Marine and Navy leaders and outside agencies have been calling attention to it for years.

This challenge has also been recognized on the other side of the Atlantic. Two Royal United Services Institute (RUSI) research fellows, Dr. Sidharth Kaushal and Dr. Jack Watling, published an article in RUSI Defence. Their overarching thesis was captured in the title of their piece, “Amphibious Assault Is Over,” and amplified in the article’s subtitle: “The conduct of amphibious operations is currently undergoing a drastic overhaul in response to an array of emerging threats.”

They suggested that: “The prospect of assaulting a hostile shore today is more daunting than ever,” and “The capacity of Marines to push inland must depend on the security of their logistical support.” While Drs. Kaushal and Watling surfaced many valid concerns regarding the efficacy of conducting opposed amphibious assaults, their thesis was not that amphibious assault operations are dead, but that we must design platforms, systems, sensors and weapons that help ensure that the assaulting forces can successfully conduct their challenging mission.

The U.S. Navy-Marine Corps Team Leverages New Technologies

Because of their long hiatus away from the U.S. Navy’s expeditionary assault ships, the U.S. Marine Corps has been especially proactive in organizing a large number of amphibious exercises, experiments and demonstrations to investigate emerging technologies (often commercial-off-the-shelf technologies—COTS) to enable expeditionary strike formations to prevail in the face of a determined adversary possessing robust A2/AD capabilities.

One U.S Navy-Marine Corps exercise, Joint Exercise Valiant Shield, focused specifically on the logistics function, something of critical importance to Marine Corps warfighters. Valiant Shield demonstrated the ability of commercial off-the-shelf technology—in this case, unmanned surface vehicles—to perform one of the more important functions needed by expeditionary formations: that of logistics.

This is a solution teed up by the U.S. Naval Institute Proceedings article cited earlier. Indeed, as the author suggested in his article:

Similar to the flexibility and the variety of logistics platforms that ground commanders have at their disposal, UUVs and USVs can increase flexibility for naval commanders. Such versatile platforms could be adapted to resupply warships at sea and Marine Corps forces on land.

Valiant Shield, overseen by Commander Marine Forces Pacific (MARFORPAC), looked to use emerging commercial off-the-shelf technology to support Marines on the beachhead during this critical juncture of an amphibious assault. To this end, a significant part of this exercise focused on logistics. And as Drs. Kaushal and Watling highlighted in their article, “The capacity of Marines to push inland must depend on the security of their logistical support.”

As noted earlier, Marines in the fight use enormous quantities of fuel, food, ammunition and other material as they attempt to move off the beachhead. All expeditionary assault planners factor logistics support in their concept of operations (CONOPS) for any amphibious operation. And given the extensive A2/AD capabilities potential peer adversaries possess, vessels providing logistics sustainment will likely be subjected to withering enemy fire as they try to deliver vital supplies to Marines on the beach.

Using manned naval craft for this sustainment mission puts operators at unnecessary risk of enemy fire, as well from near-shore obstacles that were not cleared prior to the assault phase. Using scarce manned craft to perform this mission also takes them away from more necessary roles. That is why this major Navy-Marine Corps amphibious exercise evaluated the ability of unmanned surface vehicles to conduct this sustainment mission.

MARFORPAC used USVs during exercise Valiant Shield to resupply the landing force. The exercise coordinator used a catamaran hull, 12-foot MANTAS USV to provide rapid ship-to-shore logistics sustainment.  While this small, autonomously operated, USV carried only one hundred and twenty pounds of cargo, the proof-of-concept worked and demonstrated that unmanned surface vehicles could effectively resupply troops ashore.

From Experimentation to Instantiating New Capabilities

This proof-of-concept with a 12-foot MANTAS USV achieved positive results. That said, resupply in 120-pound increments is far less than is required to provide what is needed by the Marines on the beach. The Valiant Shield exercise provided the impetus and inspiration to continue to explore the use of USVs for expeditionary force sustainment. The Navy and Marine Corps encouraged industry to “scale-up” small USVs and continue to experiment with using larger USVs to provide larger sustainment quantities. This initiative has achieved positive results.

While there are a range of larger USVs that can be evaluated by the Navy and Marine Corps, the basic specifications of the 38-foot Devil Ray “Expeditionary Class” (T38) provide an indication of the ability of USVs to provide a steady, continuous stream of logistics support to Marines on the beach. The T38 can carry a payload of 4,500 pounds. The vessel travels at cruise speed of 25 knots and draws just 18 inches of draft. Additionally—and importantly for an expeditionary assault—the T38 has a burst speed of 80 knots.

More robust logistics resupply can be provided by larger USV of the same family of Expeditionary Class unmanned surface vehicles like the Devil Ray. The next generation T82 Devil Ray, currently in its detail design phase, can carry a payload of up to 35,000 pounds. Like its sister T38, the T82 Devil Ray has a cruise speed of 25 knots and a burst speed of 80 knots. Given the speed and carrying capacity of the T38 and T82, it is readily apparent that they can support the rapid buildup of combat power on a contested beach.

This logistics concept would also complicate an adversary’s attempts to interdict resupply operations. Rather than hunting down and killing a single large, slow, vulnerable surface ship, a mother ship could deploy multiple unmanned surface vehicles outside the adversary’s weapon systems range. This would force the adversary to hunt and destroy each individual USV rather than simply tracking and destroying a surface ship moving between advanced bases or warships and resupplying them one at a time.

A New Paradigm for Marine Corps Logistics Sustainment

While there are any number of scenarios that can be offered to demonstrate how unmanned surface vessels can support Marines ashore, it is worth mentioning that while unmanned surface vessels offer substantial promise to enhance future expeditionary strike group operations, this is not to suggest that USVs completely replace traditional means of supplying expeditionary assault forces of any military. Rather, they will supplement them by providing platforms to move supplies on high-risk missions within the threat range of an adversary’s weapon systems. These unmanned surface vessels have the potential to be game changers for logistics sustainment in a contested environment.

Using a notional stand-off distance for an expeditionary strike group of 20 nautical miles, a formation equipped with four T38s traveling at their cruise speed of 25 knots could deliver 18,000 pounds of material from the expeditionary assault ships to the beach per hour, allowing the short time needed for loading and unloading the craft. Multiply that by twenty-four hours and you get a buildup of well-over 400,000 pounds of vital material per day, enough to support a substantial force of troops ashore. Using four T82s in a similar manner, the amount of vital material delivered will exceed one million pounds a day.

Until recently, getting these medium sized unmanned surface vehicles to the area of operations where they could provide logistics support to Marines on the beach was problematic. The amphibious warships comprising an expeditionary strike group are loaded with vehicles and supplies needed by their embarked Marines. What is needed is a mother ship for USVs like the T38.

These will soon enter the U.S. Navy Fleet. The Navy recently announced its intention to buy ten large, unmanned surface ships over the next five years.  The Navy envisions these LUSVs as being 200 feet to 300 feet in length and having full load displacements of 1,000 tons to 2,000 tons. These LUSVs can carry numbers of T38s combat loaded with needed supplies.

Under this CONOPS, presented in detail in a March 2022 article in Naval Engineers Journal, one or more LUSVs would be attached to an expeditionary strike group and carry these. Under this CONOPS, the expeditionary strike group can leverage the extended cruising range of the T38 to stay well clear of adversary A2/AD capabilities, as the T38 has a cruise range of 1,000-1,500 nautical miles.

Continued Experimentation is the Key to Success

Militaries worldwide have learned, often painfully, that until a promising technology if put into the hands of operators and put through its paces, it will not be part of that military’s “kit.” For this reason, the U.S. Navy and Marine Corps has evaluated the most promising USVs, in this case, the T24 Devil Ray and T38 Devil Ray, to perform the contested logistics mission in a number of recent exercises, experiments and demonstrations:

• In October 2021, U.S. Naval Forces Central Command (NAVCENT) and Task Force 59 evaluated the ability of the T12 MANTAS to perform the contested logistics mission in the Arabian Gulf. As with all CTF-59 missions, these operations were observed by multiple regional navies.
• During Operation FLEX 2022, the U.S. Navy’s Fourth Fleet used a T38 Devil Ray to test the operational viability of USVs and other new technologies to support logistics missions in a contested environment. The event was executed in close collaboration with the Navy’s Office of Naval Research SCOUT Program’s Main Logistics Event. One of the FLEX objectives was to determine the ability of USVs to autonomously deliver payloads to locations ashore.
• During REPMUS (Robotic Experimentation and Prototyping Augmented by Maritime Unmanned Systems) 2023, a Portuguese-led exercise which included a total of 17 nations and focused on maritime unmanned system experimentation, capability development and interoperability, a T24 Devil Ray demonstrated the ability of a USV to perform the contested logistics mission by hauling simulated cargo from ship to shore.
• During the U.S. Pacific Fleet-led Integrated Battle Problem 2023 (IBP-23), exercise coordinators used a T38 Devil Ray to deliver simulated logistics supplies from San Diego to San Clemente Island (a distance of 80 nautical miles), demonstrating the ability of this USV to carry a payload of several thousand pounds through significant sea states.
• While the simulated contested logistics mission described above involved carrying equipment aboard the T38 Devil Ray, an alternative method of providing logistics sustainment was also evaluated. In this case, the Devil Ray towed a “Large Test Vehicle” that displaced approximately fifteen thousand pounds, demonstrating additional versatility to deliver supplies autonomously.
• An additional mission demonstrated during IBP-23 was the value of autonomous USVs shore-to-ship connectors as well as a ship-to-shore connectors. In this case, exercise coordinators used a T38 Devil Ray to transport a simulated patient from the shore to a ship. Nine regional nations participated in this exercise conducted in the Gulf of

These are just a few of the examples of how the international maritime community has used exercises, experiments and demonstrations to evaluate the ability of autonomous, unmanned surface vessels to perform the contested logistics mission. Given the early success of these events, more work will be done in 2025 and beyond to continue to assess the ability of USVs to deliver logistics sustainment to troops ashore.

Those nations and navies with significant expeditionary assault forces would be well-served to leverage what the U.S. Navy and Marine Corps have already demonstrated in exercises such as those listed above and explore the advantages of using unmanned surface vehicles to rapidly, reliably and continuously resupply troops ashore.

This leads naturally to a broader issue, and one worthy of examination in future articles. A great deal of ink has been spilled with technologists, academics, military leaders, and others presenting their views regarding the use of unmanned systems in future wars. Recent technological advances have made it almost certain that these platforms will be enabled by artificial intelligence. This will have a profound impact on how unmanned systems will be employed in future conflicts.

This issue has received the attention of a wide range of informed leaders. Commenting on the recent book, Algorithms of Armageddon (U.S. Naval Institute Press) former Under Secretary of Defense for Policy, Michele Flournoy, noted: “National security is the realm of human activity where the risks of AI are most profound.  Those risks are being increased every day by potential opponents who are seeking to surpass the U.S. in military applications of AI.  Algorithms of Armageddon identifies these risks—and potential solutions—in a clear and accessible manner. This book should be read and discussed by everyone.”

This article first appeared in Future Warfare, issue 1-24.

It is republished with the author’s permission.

Featured Photo: The MANTAS T12 during a Valiant Shield exercise off the shore of Guam in the Pacific. Photo courtesy of Maritime Tactical Systems, Inc.

See the opening of this series:

The U.S. Military and Distributed Operations in the Pacific: The Logistics Challenge