This chapter examines the meaning of a ‘use of force’ under article 2(4) of the UN Charter, focusing on its required means. It analyses whether ‘force’ in article 2(4) is restricted to particular means, namely, if it refers to physical/armed force only, if a weapon must be employed, what is considered a ‘weapon’ and if a release of kinetic energy is required. In doing so, it discusses subsequent agreements on the meaning of a ‘use of force’ in article 2(4), including the 1970 Friendly Relations Declaration, the General Assembly’s 1974 Definition of Aggression, 1987 Resolution 42/22 and the 2005 World Summit Outcome Document. It also examines in detail the travaux préparatoires of the Friendly Relations Declaration regarding the definition of ‘force’ in article 2(4) and arguments for and against a broad interpretation. This chapter concludes that ‘use of force’ article 2(4) refers only to physical force and not to non-physical forms of coercion, that it is not necessary that a ‘weapon’ be used nor is it required that kinetic energy be released, and that physical means are not essential for an act to constitute a ‘use of force’, as what counts are its physical effects.

This chapter analyzes the negotiations for the 1970 Friendly Relations Declaration, the high-water mark of efforts by socialist and non-aligned states to win support for an expansive interpretation of national self-determination. Lawyers and diplomats from industrialized states typically argued that the right to self-determination could be exercised in a number of different ways, including loose association or confederation. They also maintained that self-determination, understood as a human right, could be secured through adequate recognition within states and did not necessarily require secession. By contrast, those speaking on behalf of the states and peoples of Asia, Africa, and other zones of decolonization framed self-determination in more capacious terms, as a right to ‘economic’ no less than ‘political’ sovereignty. Arguing that formal independence meant little if decolonized states remained hampered by earlier arrangements, they called for an international redistribution of rights and resources. They also stressed that the right to self-determination permitted armed struggle against colonial and occupying powers. Crafted through close engagement with such arguments, the 1970 resolution formalized an unsteady compromise between these two approaches, encouraging self-determination but never so far as to destabilize a fragile interstate system undergoing extensive reconfiguration.