Firstly, many thanks to Professor Adil Haque for reading my piece and for his thoughtful comments on it, both favorable and less so. Let me briefly reply to some of the points he raises.

If a State intervenes on another’s State’s territory with its consent it is, as Prof. Haque says, fair to assume there is no conflict between them. If it does so without its consent, it does not follow that a conflict necessarily exists. The ICRC commentary to me seems to clearly imply that any non-consensual intervention automatically constitutes an armed conflict simply because it is non-consensual. Consent or lack of it is an ad bellum issue to my mind and says nothing about whether actual hostilities occur or don’t. This is the reason behind my first two reasons put forward in my article. If lack of consent automatically implies a conflict, then it is hard to escape the impression that the ICRC sees it as decisive. So the distinction Prof. Haque put forward between a violation of sovereignty or an intrusion into the territorial State’s sphere of sovereignty is to me a distinction without much—indeed any—difference. My point is that an intrusion or violation of sovereignty in itself does not determine whether conflict between them exists. If that were the case, any unlawful aerial incursion would seemingly trigger an armed conflict. That would be hard to defend considering the frequency at which such incursions occur.

Certainly, if a State does not consent and actually undertakes armed action to address an intrusion, it could amount to hostilities, but that would depend on whether there was an actual use of force by one State against another and not whether there had been a non-consensual intrusion, incursion, or violation of the territorial State’s “sphere of sovereignty.” To go to what Prof. Haque describes as the “heart of the matter,” my position is that a State uses force against another State when it engages in hostilities against its armed forces, attacks national assets under the territorial State’s control, or occupies its territory. That is how I read both the Pictet Commentaries and the Tadić decision. I do not believe that this is the case when a State uses force against an armed group which is not acting in concert with the territorial State, or is under its control. If the territorial State no longer controls the territory or public property in a particular part of that State because it is under the control of the armed group, an attack against the armed group controlling it is in my view not tantamount to an attack on the territorial State because the attack is not directed against the territorial State. This is quite distinct in my view from occupation of a State’s territory. While an armed group may hold territory within a State and conduct operations from there, the State retains its sovereignty over it. Hence if a State were to intervene and take control over another State’s territory, whether this was under governmental control or had been under the control of an armed group until the intervening State displaced that control and substituted its own, this would be against the State and would therefore clearly constitute an IAC. I see no contradiction here as the two situations are quite different.

Finally, the remark that State silence is inherently ambiguous is too fast by half. Certainly there are situations where it may not be probative. But State practice and opinio juris do not only consist of positive acts and statements. It would defy reality and credibility to say that a significant number of examples of non-consensual armed intervention which have not been treated by the States in question themselves, by the UN, or by other States as constituting armed conflicts between those States over an extended period of time in different parts of the world has no significance whatsoever. On the contrary, I view it as highly significant, and that is in fact in my view the most compelling argument as to why such interventions do not necessarily result in inter-State conflicts. If none of the dogs bark there is probably a reason they don’t.

Terry D. Gill is Professor of Military Law, University of Amsterdam and Netherlands Defence Academy.