The appearance on Russian TV stations Channel One and NTV of the plans for a nuclear torpedo/unmanned underwater vehicle (UUV) has prompted much interest among observers. The leak occurred on the last day of a three day-long defence policy meeting, while President Putin was vacationing in the Black Sea resort of Sochi. Among other aspects, its probably salted warhead attracted much attention, the addition of Cobalt-59 ensuring long-lasting radiation designed to render a wide area uninhabitable for years. By exploding in shallow water, it could generate a greater amount of fallout than an equivalent device exploding in the air high above its target, the reason lying in the particles scooped up from the ground or seabed, irradiated and thrown into the atmosphere. The July 1948 Baker test in Bikini Atoll illustrated the effects of a shallow underwater explosion. Missile defence experts have noted how, in line with Russian commentary, the system seems to be designed to bypass Western progress in this field. There’s another significant aspect of the possible construction of this weapon: its impact on the international law of the sea.

The leaked chart included some text, outlining the capabilities of ‘Ocean Multipurpose System Status-6’, designated as ‘Kanyon’ by the Pentagon. Designed to cause ‘assured unacceptable damage’, its detonation ‘in the area of the enemy coast’ would prompt ‘extensive zones of radioactive contamination’, preventing ‘military, economic, business or other activity’ for a ‘long time’. Some analysts are calling it a ‘Doomsday weapon‘, with and US Senator Tom Cotton (R-AR) labelling it ‘destabilizing‘.

From an international law of the sea perspective, there are at least three issues that need discussion: whether a submarine carrying nuclear torpedoes may carry out innocent passage through another country’s territorial waters, the 1971 treaty banning nuclear weapons on the seabed, and whether a coastal state may restrict the presence of submarines carrying nuclear torpedoes in its EEZ.

The issue of submarines operating near enemy ports was discussed both during and after the Cold War, although the context was usually US attack submarines tracking Soviet strategic boats, and Moscow’s fear of losing the latter. In 1998 Eugene Miasnikov said that ‘an agreement between the US and Russia on limiting submarine covert operations at certain areas could be a substantial addition to the bilateral Agreement on the Prevention of Incidents On and Over the High Seas’. As its name implies, this treaty didn’t cover submarines, and despite some incidents ‘neither side has pushed the issue‘.

Article 19 of UNCLOS deals with innocent passage through territorial waters, stating that it ‘is innocent so long as it is not prejudicial to the peace, good order or security of the coastal State’, and adding that it ‘shall be considered’ to be so if it engages in a number of activities, which include ‘any threat or use of force’ (a), ‘any exercise or practice with weapons of any kind’ (b), and ‘the launching, landing or taking on board of any military device’ (f). While launching a nuclear torpedo within territorial waters would clearly fall outside innocent passage, things get more complex if it’s an unmanned undersea vehicle (UUV). In that case, there’s no ‘launching’ of a military device, since the vessel itself is the device. Could that UUV conduct innocent passage? Or would it be considered an autonomous torpedo? What if the warheads were detachable, consisting of either torpedoes or mines (two concepts that are gradually converging)? Article 20, usually disregarded, says submarines must emerge when conducting innocent passage. It’s unclear whether this also applies to unmanned systems.

The Treaty on the Prohibition of the Emplacement of Nuclear Weapons and Other Weapons of Mass Destruction on the Seabed and the Ocean Floor and in the Subsoil Thereof doesn’t seem to ban Status-6-type weapons. The reason for this is that UUVs are designed to sail underwater, rather than be statically placed on the seabed or drilled into it. However, in contrast with a normal torpedo (even of the nuclear kind deployed in Cuba in 1962), or a nuclear mine or depth charge, they aren’t meant to explode in contact with or near a vessel, but rather land and the seabed. Not just to make sure the explosion takes place close to a coastal city, but to guarantee plenty of fallout, which together with the Cobalt-60 (half life 5.27 years) resulting from the explosion would render a large area uninhabitable. An expansive interpretation of the Treaty might therefore also cover strategic (that is, city bound) nuclear torpedoes. Furthermore, nuclear drones could be seen as falling more clearly within the treaty if they were seafloor-crawling or rested on the seabed.

Concerning the rights of coastal states in their EEZs, the US has consistently pressed for a wide interpretation of freedom of navigation, rejecting the restrictive views held by countries such as China. Washington has resisted Beijing’s attempts to restrict intelligence collection in its EEZ, a dispute that has led to some incidents. We may ask ourselves whether the deployment of nuclear drones may prompt US policymakers to pragmatically moderate their enthusiasm for freedom of navigation. That could perhaps take the form of some sort of informal understanding, for which a precedent may be that concerning the non-deployment of ballistic missiles in Cuba, settling the 1962 crisis. The understanding was confirmed during the 1970 Cienfuegos Crisis, when Washington successfully pushed Moscow to terminate work on an strategic submarine base in that Cuban port.

We need to remember that international law isn’t immutable, but subject to myriad factors, including technological developments and changes in relative power. Thus, the development of strategic nuclear drones may prompt questions concerning existing rules, and perhaps their evolution.