Irreconcilable Differences: The Thresholds for Armed Attack and International Armed Conflict

46 Pages Posted: 29 May 2020 Last revised: 9 Jun 2020

Date Written: March 18, 2020


This article explores the gap between the definition of armed attack and the threshold for international armed conflict to identify possible consequences of the different definitions for the application of either or both bodies of law and to consider whether efforts to reconcile the different meanings are feasible and, more importantly, desirable or problematic. Although the dangers of conflating jus ad bellum and LOAC are well-known and thoroughly examined in jurisprudence and academic literature, the interplay between these two foundational concepts in the two bodies of law remains unexplored. These two definitions or concepts are the building blocks on which much of the international law authority regarding the use of force resides. Armed attack is the threshold for the use of force in self-defense and therefore forms an essential component of the jus ad bellum and, in effect, serves as a gatekeeper for the acceptable use of force. The existence of an international armed conflict triggers the application of LOAC, with all of its attendant authorities, obligations, rights and protections. Both terms are central to understanding the parameters for the use of force in various ways — and yet each has a different meaning, a different pedigree, and potentially consequential effects on the ability of the other term to serve its purpose. The interplay and different thresholds for armed attack and for international armed conflict raise challenging questions about the co-existence of the two bodies of law, namely the consequences of an international armed conflict triggered by acts or force that lie below the threshold for armed attack or other triggering of jus ad bellum. Can force be used and how should it be judged in such circumstances?

The first section briefly presents the definition of armed attack and the threshold for international armed conflict, with a focus on the purpose of the particular thresholds and definitions for the two terms in order to provide a foundation for the main comparisons and discussion in the rest of the article. Part II examines the gap between the respective meanings of the two concepts and the potential legal consequences. In particular, this section analyzes two primary, but opposing, interpretive effects of the gap between the meanings of armed attack and international armed conflict: first, the use of force in situations falling below the threshold of armed attack; and second, the possibility that an international armed conflict could exist without the states engaged in such conflict having the authority to use force against the adversary. Each of these possibilities raises a red flag within one body of law but at the same time hews closely to the basic concept or goals of the other, raising the question of whether this gap matters and, if so, whether some reconciliation is appropriate. The third section addresses this final question, that of reconciliation between the two definitions and examines what such reconciliation might look like. More important, attempts at reconciliation could cause a severely damaging blow to one or the other body of law, such that preserving the gap — that is, agreeing to disagree, in effect — is the better course of action.

Keywords: international armed conflict, law of armed conflict, jus ad bellum, self-defense, United Nations Charter, armed attack, international humanitarian law, law of war

Suggested Citation

Blank, Laurie R., Irreconcilable Differences: The Thresholds for Armed Attack and International Armed Conflict (March 18, 2020). Notre Dame Law Review, Vol. 96, 2020, Emory Legal Studies Research Paper No. 20-8, Available at SSRN:

Laurie R. Blank (Contact Author)

Emory University School of Law ( email )

1301 Clifton Road
Atlanta, GA 30322
United States
404-712-1711 (Phone)


Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Abstract Views
PlumX Metrics