From the fact that all States have an interest in the fulfilment of an obligation it does not necessarily follow that those norms are peremptory - that is to say, they do not necessarily render conflicting obligations null and void.
履行某项义务涉及所有国家，从这一事实出发未必就能下结论说，这些规范都是强制性的——也就是说，它们未必使冲突义务无效。