Use of Force (Public International Law and Armed Conflicts)

Article 2(4) of the Charter of the United Nations (UN Charter) introduced for the first time a comprehensive ban on the use of force in international relations between states. Indeed, the use of force is prohibited outright, applying not only to the waging of war (as in the Briand-Kellogg Pact of 1928) but also to forcible measures short of war such as intervention, blockades, and reprisals. Moreover, the ban extends not only to the actual use of force but also to its threat. The prohibition is accompanied by a robust system of collective security embodied primarily in Chapter VII of the UN Charter. As a matter of interpretation under the Vienna Convention on the Law of Treaties 2 (Vienna Convention), the content and scope of
the prohibition must be construed in context, that is, in the light of other relevant provisions in the UN Charter and its Preamble; ‘any agreement relating to the treaty which was made between all the parties in connection with the conclusion of the treaty’; and ‘any instrument which was made by one or more parties in connection with the conclusion of the treaty and accepted by the other parties as an instrument related to the treaty’.