Abstract While irreversibility of nuclear arms control and disarmament measures can be supported by compliance with applicable legal norms, the existing treaty regulation has serious gaps: pertinent treaties are not universally applicable; limitations on missiles as important carriers of nuclear warheads have been abrogated; the strategic doctrines of nuclear weapons powers are not fully transparent, and while the latter may strengthen the effectiveness of nuclear deterrence, it also raises questions as to compliance with fundamental obligations to refrain from a threat or use of force and to settle international disputes by peaceful means. There are certain principles of general international law that can and should be used in international cooperation to overcome nuclear crisis situations and strengthen international security: fundamental norms regarding the non-proliferation of nuclear weapons and nuclear disarmament under strict and effective international control have an erga omnes character and are accepted and recognized by the international community of States as a whole. Furthermore, general rules of international responsibility are fully applicable in the law of nuclear arms control and disarmament. It is in this sense that irreversibility in nuclear arms control and disarmament is served by legal principles and rules, which require States to comply with existing obligations and to cooperate for the maintenance of peace and security.