Ken Watkin’s thoughtful piece last week — Reflections on Targeting: Looking in the Mirror — addressed the debate on the targeting of war-sustaining economic enterprises as part of the military response to the Islamic State. This comment does not address his general thesis, which raises difficult questions going to the targeting of economic and financial infrastructure. It goes, rather, to his conclusion on the issue of the targeting of those who provide “material support” essential to terrorist attacks.

In the concluding section of his piece — “Personnel Reflections” — Ken refers to the Self-Defense Principles published under my name in the American Journal of International Law in 2012, noting inter alia that:

Principle 7 suggests armed action can be taken in self-defense against those taking “a direct part in … [armed] attacks through the provision of material support essential to the attacks.” It is not clear what “material support” encompasses in these Principles, or its relationship to DPH.

He concludes with the observation that “material support” is an exceptionally broad concept under US law and that, to ensure clarity and that there is no conflict with the international consensus on this issue, “it should be emphasized that the broader ‘substantial’ or ‘material’ support terms are not relied on when targeting in a self-defense or any other context.”

I agree with this cautionary observation. As regards Ken’s reference to Principle 7 of the Self-Defense Principles, however, Principles with which Ken has first-hand familiarity, there are two points that warrant elaboration to avoid mis-appreciation of what was set out therein.

The first point goes to what Principle 7 actually says, including in its qualifying footnote on the issue of targeting those who provide material support essential to terrorist armed attacks. The text of Principle 7 and its associated footnote read as follows:

7. Armed Action in self-defense may be directed against those actively planning, threatening, or perpetrating armed attacks. It may also be directed against those in respect of whom there is a strong,[fn] reasonable, and objective basis for concluding that they are taking a direct part in those attacks through the provision of material support essential to the attacks.

[fn] The addition of the adjective “strong” to the “reasonable and objective basis” formula … raises the standard that is required for the conclusion in question, given that this assessment would form the basis for taking action against persons other than those planning, threatening, or perpetrating an armed attack.

The second point is to recall my observations on the language of “those providing material support essential to [such] attacks” in my AJIL response to the comments on the Self-Defense Principles. Noting the difficult questions around the issue of against whom armed action by way of self-defense may be directed, I commented as follows (p. 584):

The reference in principle 6 (and, in slightly different formulation, in principle 7) to “those providing material support essential to those attacks” is problematic and did not attract unreserved agreement from among those engaged in the exercise [of formulating the Self-Defense Principles]. There was, however, an appreciation that self-defense action directed against a provider of arms essential for the carrying out of an attack may be permissible, depending on the circumstances, hence the inclusion of a hedged reference to persons providing material support. But it is difficult to identify the line between such conduct and the provision, for example, of financial support, which would not attract common agreement as warranting a self-defense response. The use of the term material support has also become problematic given its controversy in a U.S. military commissions context.

These points add support to a cautionary approach to the question of targeting financiers and others providing economic support essential to terrorist armed attacks. The first point affirms agreement that there is, and should be, an especially high bar to the targeting of persons other than those actively engaged in the planning, threatening and perpetrating of an armed attack. The second point notes disagreement on whether it is permissible to target those providing financial support essential to terrorist armed attacks.

It also highlights the difficulty in drawing a bright line between those whose support for an armed attack is sufficiently direct and significant as to make them potentially lawful targets and those whose support is less direct, even if it is still significant, as to make their lawful targeting questionable. While addressing where this line falls in any given circumstance may ultimately be an operational question, there is no consensus that it is permissible to target those who provide material support for terrorist armed attacks, but who are not otherwise engaged in active attack planning and perpetration.