RECOGNIZING OUR CO-BELLIGERENT STATUS

A state becomes a party to an ongoing interstate armed conflict when it provides significant operational, logistical, or intelligence support to an existing, active belligerent. States that are currently providing Ukraine with such assistance have thus already entered the armed conflict against Russia. That conclusion should not, however, lead those states to curtail their support of Ukraine’s war effort. Instead, they should redouble their efforts to support the collective defense of Ukraine in full recognition of their participation in the war.

A state becomes a belligerent when it participates in hostilities “indirectly.” A state participates in hostilities when it carries out operational, logistical, or intelligence functions that are integrated into a military operation conducted by an existing belligerent. A state renders such support when, for example, it provides a belligerent with intelligence that is immediately used to conduct attacks or helps a belligerent coordinate its military operations. Moreover, a state participates in hostilities when it supplies an active belligerent with operational, logistical, or intelligence assistance that directly contributes to the supported party’s overall military effort in the conflict. Critically, that includes circumstances in which a state supplies military matériel—arms, ammunition, and other military equipment—to an active belligerent. The “supply of arms and munitions” to an active belligerent constitutes “a direct contribution to its military resources, and as such is a participation in the war.” Accordingly, a state enters an ongoing interstate armed conflict as a belligerent when it supplies an active belligerent with significant operational, logistical, or intelligence assistance that either is integrated into a specific military operation carried out by the supported party or otherwise directly contributes to the supported party’s overall military effort in that conflict.

Many NATO allies have entered the Russo-Ukrainian War as belligerents due to their significant indirect participation in hostilities. The United States, for example, has supplied massive of military matériel and security assistance since the war began. Washington is also sharing increasingly extensive amounts of intelligence—apparently including detailed, real time targeting information—with Kyiv to help it effectively conduct operations against Russian forces. That assistance is significant both in absolute terms and because it has been integral to Ukraine’s war effort against Russia. It has enabled Kyiv to reverse the initial Russian offensive of the war, and will remain decisive with respect to Ukraine’s capacity to effectively resist Russian aggression going forward.

Critically, moreover, those U.S. efforts constitute the kinds of significant direct military support for an active belligerent’s war effort that have previously led states and scholars to recognize a supporting state as a belligerent in an ongoing armed conflict. For example, early in the Second World War prior to Pearl Harbor, many scholars concluded that the United States was engaged in an armed conflict against Nazi Germany via its efforts to supply the United Kingdom with substantial amounts of military matériel. The German government similarly identified the United States as an enemy belligerent following the onset of those initiatives.

NATO states should affirmatively recognize their belligerent status, as that would bolster the legitimacy of forcible responses to indirect armed aggression perpetrated by Russia. It is for NATO states to recognize that their indirect participation in the Russo-Ukrainian War makes them parties to that conflict. Far from curtailing their assistance, then, NATO states should further expand their role in the Russo-Ukrainian War as the collective “arsenal of democracy” in a new era of authoritarian aggression.