Identifying the range of lawful reactions to non-performance of treaties is still problematic, as shown by the case concerning the Application of the Interim Accord of 13 September 1995 (FYROM/Greece). After reviewing the current understanding of the relationship between the law of treaties and the law of international responsibility, the author analyses the legal regime pertaining to suspension and termination of treaties on grounds of breach, on the one hand, and, on the other, to countermeasures, arguing that the exceptio inadimpleti contractus may still play an independent, albeit limited, role as a reaction to lawful non-performance of international treaties.
