The Final Frontier of Cyberspace: Ensuring that Submarine Data Cables are Able to Live Long and Prosper (Part II)

[Tamsin Phillipa Paige is a Lecturer at Deakin Law School. Douglas Guilfoyle is an Associate Professor at UNSW Canberra and Rob McLaughlin is a Professor at the Australian National Centre for Ocean Resources & Security, University of Wollongong.]

In Part One of this blog series we considered the ways in which international law addresses severing submarine data cables outside armed conflict, noting that the intentional cutting of a submarine data cable by a state or non-state belligerent group is unlikely to be characterised as anything other than an armed attack. This conclusion necessitates an examination  of how the law of armed conflict (LOAC) and the law of naval warfare (LoNW) consider the targeting of submarine data cables during an armed conflict. Recently, James Kraska considered this question concluding that the governing legal rules were those of neutrality. While we agree that in an ideal world according submarine cables the status of neutral object would be the best solution, we respectfully disagree with his conclusions. Nonetheless, by a different path we reach conclusions with the same practical effect. In considering the targeting of submarine cables under LOAC and LoNW, we will first look at the history of cable cutting as a legal concern and through the lens of state practice. We will then consider modern instances of wartime cable cutting, concluding that while submarine data cables may be considered a valid military target, proportionality tests would always fail given that the significant scale of civilian harm that would result would necessarily outweigh any potential military advantage.

The History of Targeting Submarine Cables

In the lead up to World War I, a number of instruments considered whether submarine cables could be a valid target of military operations. These included the 1884 Paris Convention, the 1902 Institute for International Law resolution, and the 1900 US Naval War code; however, the most significant attempt to grapple with the issue of LOAC and the targeting of submarine cables was the 1907 Hague Regulations Respecting the Laws and Customs of War on Land. This stated in Article 54:

Submarine cables connecting an occupied territory with a neutral territory shall not be seized or destroyed except in the case of absolute necessity. They must likewise be restored and compensation fixed when peace is made.

This articulation in the 1907 Hague Regulations gave rise to a more detailed set of principles in the 1913 Oxford Manual of the Laws of Naval Warfare, which stated (at page 64):

C. Submarine cables.

In the conditions stated below, belligerent States are authorized to destroy or to seize only the submarine cables connecting their territories or two points in these territories, and the cables connecting the territory of one of the nations engaged in the war with a neutral territory.

(1) The cable connecting the territories of the two belligerents or two points in the territory of one of the belligerents, may be seized or destroyed throughout its length, except in the waters of a neutral State.

(2) (a) A cable connecting a neutral territory with the territory of one of the belligerents may not, under any circumstances, be seized or destroyed in the waters under the power of a neutral territory.

(b) On the high seas, this cable [connecting a neutral territory with the territory of one of the belligerents]

may not be seized or destroyed unless there exists an effective blockade and within the limits of that blockade, on consideration of the restoration of the cable in the shortest time possible.

(c) This cable [connecting a neutral territory with the territory of one of the belligerents] may be seized or destroyed on the territory of and in the waters belonging to the territory of the enemy for a distance of three marine miles from low tide.

(d) Seizure or destruction may never take place except in case of absolute necessity.

(3) In applying the preceding rules no distinction is to be made between cables, according to whether they belong to the State or to individuals; nor is any regard to be paid to the nationality of their owners. (4) Submarine cables connecting belligerent territory with neutral territory, which have been seized or destroyed, shall be restored and compensation fixed when peace is made.

State practice throughout World War I demonstrates that these requirements (absolute necessity and naval blockade) may be considered lex ferenda. World War I-era lex lata (as gleaned through state practice) shows us that while cutting of neutral state to neutral state cables was not permitted, cutting of cables to belligerent states was lawful even without necessity, or blockade. This practice continued through World War II before the issue dropped off international lawyers’ radar, mainly as a result of the shift away from telegraphic to wireless communications. This led to the 1995 San Remo Manual and the 2017 Tallinn Manual 2.0 both asserting that cables are subject to the standard test for determining military objectives with scant concern for the nature of submarine cable infrastructure and its importance to civilian life.

Contemporary Cable Cutting: Neutrality or Permissible Target?

The question whether a submarine data cable can be considered a neutral object appears to have been answered already by historical state practice and their categorisation as potential military targets in the San Remo and Tallinn Manuals. While historically this targetability was restricted to cables being used by belligerents, in a contemporary context such a distinction is unmanageable. This follows from the volume of traffic from multiple states traveling through every cable at all times. Isolating belligerent data traffic is not a reasonable expectation. So, can submarine cables ever be a legitimate military target?

Article 52(2) of the 1977 Additional Protocol 1 and Rule 40 of the San Remo Manual define a military objective as:

… military objectives are limited to those objects which by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage. 

Given the evidence that cutting of submarine data cables can, among other things, inhibit communications and halt UAV activities, it is clear that the use of submarine data cables could certainly make ‘an effective contribution to military action’ such that their destruction could offer ‘a definite military advantage’. Consequently, the key issue is whether such action could satisfy the proportionality test? The doctrinal approach to the proportionality test is focusses upon the language of Additional Protocol I Article 57(2)(a)(iii): The belligerent should ‘refrain from deciding to launch any attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.’ We suggest that any application of this test will always come back in the negative. This is because the combination of the scale of impact on civilian social and economic infrastructure, and the likelihood of this damage spreading beyond the targeted state to neutral third states, can only be excessive in relation to any military advantage. This conclusion is grounded in the interconnected nature of the Internet through submarine data cables, and the sheer extent of foreseeable civilian harm that would result (and this is quite separate to considerations flowing from the attendant obligation of constant care). When all of these consequences are considered it is nigh impossible for any military objective to be considered proportional to the widespread collateral damage that would occur to civilians resulting from the cutting of a submarine data cable. Thus, while a formal recognition of neutrality of submarine cables (as suggested by Kraska) would be preferable, we contend that a conventional approach to the proportionality test (when done in good faith) results in the same net effect and is more politically realistic than advocating a new neutrality norm. Thus we conclude that the severing of submarine data cables, while theoretically permissible under LOAC and LoNW, is functionally unlawful.