128 Report of the International Law Commission on the work of its fifty-third session cannot solve.734 Paragraph 2 (b) can do no more than set out the general principle. (13) Paragraph 2 (b) refers to the State claiming “[p]erformance of the obligation of reparation in accordance with the preceding articles”. This makes it clear that article 48 States may not demand reparation in situations where an injured State could not do so. For example, a demand for cessation presupposes the continuation of the wrongful act; a demand for restitution is excluded if restitution itself has become impossible. (14) Paragraph 3 subjects the invocation of State responsibility by States other than the injured State to the conditions that govern invocation by an injured State, specifically article 43 (notice of claim), 44 (admissibility of claims) and 45 (loss of the right to invoke responsibility). These articles are to be read as applicable equally, mutatis mutandis, to a State invoking responsibility under article 48. Chapter II COUNTERMEASURES Commentary (1) This chapter deals with the conditions for and limitations on the taking of countermeasures by an injured State. In other words, it deals with measures that would otherwise be contrary to the international obligations of an injured State vis-à-vis the responsible State, if they were not taken by the former in response to an internationally wrongful act by the latter in order to procure cessation and reparation. Countermeasures are a feature of a decentralized system by which injured States may seek to vindicate their rights and to restore the legal relationship with the responsible State which has been ruptured by the internationally wrongful act. (2) It is recognized both by Governments and by the decisions of international tribunals that countermeasures are justified under certain circumstances.735 This is reflected in article 22 which deals with countermeasures in response to an internationally wrongful act in the context of the circumstances precluding wrongfulness. Like other forms of self-help, countermeasures are liable to abuse and this potential is exacerbated by the factual inequalities between States. Chapter II has as its aim to establish an operational system, taking into account the exceptional character of countermeasures as a response 734 See also paragraphs (3) to (4) of the commentary to article 33. 735 For the substantial literature, see the bibliographies in E. Zoller, Peacetime Unilateral Remedies: An Analysis of Countermeasures (Dobbs Ferry, N.Y., Transnational, 1984), pp. 179–189; O. Y. Elagab, The Legality of Non-Forcible Counter-Measures in International Law (Oxford, Clarendon Press, 1988), pp. 227–241; L.-A. Sicilianos, Les réactions décentralisées à l’illicite: Des contre-mesures à la légitime défense (Paris, Librairie générale de droit et de jurisprudence, 1990), pp. 501–525; and D. Alland, Justice privée et ordre juridique international: Etude théorique des contre-mesures en droit international public (Paris, Pedone, 1994). to internationally wrongful conduct. At the same time, it seeks to ensure, by appropriate conditions and limitations, that countermeasures are kept within generally acceptable bounds. (3) As to terminology, traditionally the term “reprisals” was used to cover otherwise unlawful action, including forcible action, taken by way of self-help in response to a breach.736 More recently, the term “reprisals” has been limited to action taken in time of international armed conflict; i.e. it has been taken as equivalent to belligerent reprisals. The term “countermeasures” covers that part of the subject of reprisals not associated with armed conflict, and in accordance with modern practice and judicial decisions the term is used in that sense in this chapter.737 Countermeasures are to be contrasted with retorsion, i.e. “unfriendly” conduct which is not inconsistent with any international obligation of the State engaging in it even though it may be a response to an internationally wrongful act. Acts of retorsion may include the prohibition of or limitations upon normal diplomatic relations or other contacts, embargoes of various kinds or withdrawal of voluntary aid programmes. Whatever their motivation, so long as such acts are not incompatible with the international obligations of the States taking them towards the target State, they do not involve countermeasures and they fall outside the scope of the present articles. The term “sanction” is also often used as equivalent to action taken against a State by a group of States or mandated by an international organization. But the term is imprecise: Chapter VII of the Charter of the United Nations refers only to “measures”, even though these can encompass a very wide range of acts, including the use of armed force (Articles 39, 41 and 42). Questions concerning the use of force in international relations and of the legality of belligerent reprisals are governed by the relevant primary rules. On the other hand, the articles are concerned with countermeasures as referred to in article 22. They are taken by an injured State in order to induce the responsible State to comply with its obligations under Part Two. They are instrumental in character and are appropriately dealt with in Part Three as an aspect of the implementation of State responsibility. (4) Countermeasures are to be clearly distinguished from the termination or suspension of treaty relations on account of the material breach of a treaty by another State, as provided for in article 60 of the 1969 Vienna Convention. Where a treaty is terminated or suspended in accordance with article 60, the substantive legal obligations of the States parties will be affected, but this is quite different from the question of responsibility that may already have arisen from the breach.738 Countermeasures involve conduct taken in derogation from a subsisting treaty 736 See, e.g., E. de Vattel, The Law of Nations, or the Principles of Natural Law (footnote 394 above), vol. II, chap. XVIII, p. 342. 737 Air Service Agreement (see footnote 28 above), p. 443, para. 80; United States Diplomatic and Consular Staff in Tehran (see footnote 59 above), p. 27, para. 53; Military and Paramilitary Activities in and against Nicaragua (see footnote 36 above), at p. 106, para. 201; and Gabčíkovo-Nagymaros Project (see footnote 27 above), p. 55, para. 82. 738 On the respective scope of the codified law of treaties and the law of State responsibility, see paragraphs (3) to (7) of the introductory commentary to chapter V of Part One.