Military Alliances under International Law

While military alliances have always been an important subject of research in international relations, relatively little study has been conducted on them in international law. Even though military alliances have been featured in the wider discussions on regional orders under international law, little systematic effort has been made to assess the extent to which various actions that are routine for or structured into the design and operation of military alliances are compatible with international law. This article aims to fill this gap by examining the implications of certain activities of military alliances under three areas of international law and is divided into three substantive sections. The first section examines how activities such as military exercises, force concentration and coercive demands, when undertaken by a military alliance, could heighten the risk of their violation of the prohibition of the threat of force under the UN Charter. The second section examines how certain standing arrangements of military alliances pre-dispose them to intervene in civil strife in allies or potential allies in potential violation of the norm against intervention in the domestic affairs of another State. The third section examines how, despite their often-explicit deference to the UN Charter, military alliances operate in tension with the collective security architecture of the UN and suggests ways to harmonise them. The article concludes that the sovereign rights of States to form military alliances do not create a carte blanche for military alliances to operate freely from any restraint of international law and calls for a more proactive approach to maintaining international peace and security in view of the complex nature of certain activities of military alliances under international law.