The growing range and changing nature of unilateral sanctions have seen the emergence of a new label of so-called ‘secondary’ sanctions, as opposed to the more traditional ‘primary’ sanctions. While there is no accepted legal definition of secondary sanctions, in essence, secondary sanctions restrict economic transactions between third countries which may be entirely lawful under the law of these countries. Their extraterritorial character gives secondary sanctions their distinctive and particularly controversial character. Secondary sanctions create inter-State tension and may possibly violate a number of public international law regimes. They may harm the politico-economic interests of third States and cause headaches for private economic operators, whose potential exposure to secondary sanctions complicates the already complex web of multi-jurisdictional norms governing their international business transactions.