The issue of enforcement by means of non-forcible measures is one of the least developed areas of international law. Two legal regimes are relatively clear-nonforcible countermeasures taken by States (countermeasures) and non-forcible measures taken by international organizations (sanctions). The development of a restricted doctrine of countermeasures as the modern accepted form of self-help is considered, along with the partial centralization of coercion in international organizations. The also provided for the application of such measures, 3 a trend that was to be followed by some other regional organizations. A self-help system of non-forcible measures deriving from an earlier period of international relations, had to coexist with a system of centralized 'sanctions' based on notions of hierarchy and governance. In addition to the uncertainty that existed between the institutional level and the customary level, there was also a lack of clarity in the relationship between the universal organization (the United Nations) and other organizations. Article 53(1) of the UN Charter seems to provide that any non-forcible measures taken by regional organizations that amount to 'enforcement action' requires the authorization of the Security Council.The concept of lawful non-forcible measures survived the new world order of the post-1945 period. Article 2(4) of the Charter prohibited the 'threat or use of force', and this was clearly construed as military force (but see Paust and Blaustein, 1974, p 417).State practice in the immediate post-1945 period provided evidence of the continuing relevance of non-forcible measures. As Elagab states: '[r]egardless of whether the conditions of legality had been complied with in each case, the crucial feature was the very fact of such claims being staked at all. This provides a presumption of continuity of counter-measures as a viable mode of redress' (Elagab, 1988, p 38). In the first decade after the UN Charter the USA adopted, inter alia, measures freezing the assets of China, Bulgaria, Romania, and Hungary. The coinage of the term 'countermeasures' in the Air Services Agreement case of 1978 4 and the codification of countermeasures by the International Law Commission (ILC), culminating in Chapter III of the Articles on State Responsibility of 2001, 5 represent its consolidation in the structures of international law.The inclusion of countermeasures was seen as a way of at least partially filling the lack 3