We don’t often spend a lot of time thinking about the morality of submarine warfare. It’s a small and secretive world that rarely seeks attention. It did, however, surface recently with the sinking of Iranian warship IRIS Dena on March 4, 2026.
When looking at this incident, it is important to take a deep breath. In the age of cognitive, cyber, and information operations it is challenging to understand what is true. In philosophical terms, war is always surrounded by epistemic uncertainty—the fog of war—but now battles are fought over our perception of fact, and our moral cognition is perhaps the most important terrain of the cognitive battlefield.
The first thing to understand about the incident is the status of the units. USS Charlotte is an American nuclear-powered (not nuclear-armed) attack submarine. The Dena is a Moudge-class destroyer. Dena is set up for defense against submarines, aircraft, and missiles. It can carry anti-ship missiles. The submarine has one primary role, to attack surface and sub-surface vessels, and it is armed with heavy-weight torpedoes, though it can also fire land and surface attack missiles.
Next, what were these two doing off Sri Lanka, and is that relevant? The Dena was participating in a multinational exercise hosted by the Indian Navy. Is this significant? Much has been made of it. It could be significant because it has been used to drive a wedge between what is conventionally accepted in war and what is morally accepted. That is, in war we tend to express conventional rules and norms that are accepted by the combatants for their efficacy at mimicking what is morally acceptable. They tend rules that are easier to follow than more complex moral arguments. Convention codifies most but, not all our, moral convictions.
The significance of the exercise is that the Dena was “disarmed” as a condition of its participation, according to some reports. This would be the tip of the wedge between the conventional assertion that units of one combatant state can be permissibly targeted by the other. If there is reason to believe that one unit did not pose a threat, then the targeting is not automatically morally permissible despite the unit’s status as an enemy combatant.
There is a strong moral argument that the conventional rule assumes an imminent or potential danger. Much has been made about the phenomenon of combatants having resistance to killing others in vulnerable positions. And there is good reason for that argument, as most combatants are only partially consenting participants, and if their lives can be spared, they ought to be. The weapons (ships) are often the threat and not the people; this is so even without armament as the ship has latent capability through its sensors and communications equipment.
The other element that is supposed to be significant about the exercise is that the submarine would have known the location of the Dena. This is supposed to show an unfair advantage. If so, it is not a great advantage. Surface ships are relatively easy to localize given aircraft and satellites. If the Dena had been exercising in a multinational setting, they would be aware of the intelligence-gathering opportunity this presents (through acoustic, radar, and signals signatures). If this fact is morally significant, it is significant because it gives the Dena two pieces of information, firstm that there is an adversary’s submarine collecting intelligence in the area, and second, that it probably knows where you are. These are both vital pieces of information for setting sensor and personnel defensive postures.
That the ship was outside of the Iranian- and U.S.-declared maritime warning zones (the area where maritime combat is expected) may be significant. Such a fact does not mean that hostilities conventionally or morally cannot take place. Indeed, the captain of the Argentine warship Belgrano—the actual last warship sunk by torpedo, which was sunk outside an exclusion zone—accepted that his sinking was not “a betrayal.” Being outside a zone where combat is expected increases the likelihood of non-combatants in the area. There is a strengthened moral requirement, in such a case, to discriminate and aim correctly.
The Dena‘s being disarmed is highly implausible. The exercise had live-firing opportunities. If being “disarmed” was a condition of joining the exercise, that would mean that there were ammunition (status) restrictions and not prohibitions. Typically, ammunition is made safe or inaccessible for the duration of an exercise. Some live ammunition would be available for the scheduled live-fire events during the exercise. It is unlikely that the Dena was unarmed, though plausibly it was not armed to a wartime level. It would be negligent of the Dena, knowing that a U.S. submarine is probably in the area, not to be in a high degree of sensor and personnel readiness for a subsurface threat.
What of the U.S. submarine’s responsibility? It has an obligation to ensure discrimination and proportionality. A submarine does not see its target when tracking. It will use inference and deduction to narrow its focus and knowledge. Subsurface warfare is an epistemological problem of managed uncertainty. To achieve certainty, a submarine can use its periscope to identify and discriminate its target visually, through radar, or with radio signals.
The submarine did this, as there is a recording. A periscope exposes the submarine and can be detected visually or by radar. There are also reports that the submarine gave two warnings. This also exposed Charlotte and it gave Dena’s crew time to escape to life rafts. The target is the Dena and not the crew. Warning makes the attack more proportional. A heavyweight torpedo is one of the most lethal weapons in naval warfare; that so many crew members survived is an indication of warning partially heeded.
The final issue is what happened after the torpedo was fired. Proportionality demands that if loss of life can be minimized, then it ought to be. There are no reports that Charlotte aided in the rescue. The idea of necessity would mitigate an obligation to take those stranded on board, but some form of aid—helping survivors into life rafts, providing first-aid—is minimally required, if doing so does not place the Charlotte in danger.
Given the distance from hostilities and the exclusion zone, any presumption against surfacing is reversed, and once engaged in rescue operations, the submarine is afforded a degree of protection (conventionally and morally). There are also reports that the submarine helped coordinate the Sri Lankan rescue; though commendable, this does not help the urgent requirement to rescue after the sinking.
It takes time for details to emerge, and there may still yet be more information. The U.S. Secretary of Defense’s emphasis on lethality and comments about not providing quarter diverts attention away from what Charlotte did right—getting visual confirmation and providing warning—but it may have dissuaded them from taking the necessary step of aiding survivors. It is worth remembering that, as philosopher and veteran John Rawls points out in “The Law of Peoples,” the pronouncements of leaders impact the attitudes and actions of those fighting and foreshadow what the end of hostilities will look like.
Christopher M. Maier
Christopher is a PhD candidate and lecturer in philosophy at the University of Victoria with research interests in military, political and moral philosophy. He is a retired Lieutenant-Commander, former Commandant of Naval Fleet School Pacific, and was also the commander of that school’s tactics division. He served as Executive Officer in His Majety’s Canadian Ships Brandon, Edmonton and Yellowknife and has deployed to the Eastern Pacific on OP Caribbe, Canada’s contribution to the War on Drugs, to Afghanistan as part of Headquarters Regional Command South, and to the Sudan as a Military Observer for the United Nations Mission in Sudan (UNMIS). He has commendations from the Chief of the Defence Staff, Commander Royal Canadian Navy, and Commander Canadian Expeditionary Forces. He is an associate fellow of the Nautical Institute. He has published on military ethics in the Canadian Journal of Practical Philosophy.
