The history of economic sanctions as a tool of foreign policy goes back almost 2,500 years. The first known implementation of these punitive measures by one country against another was in 432 BC, when Athens imposed a trade embargo on the city-state of Megara. Since that date, the use of sanctions has intensified from century to century until it has reached its peak in our time. Researchers, however, have been unable to provide a universal definition of sanctions. The most commonly used explanation of the term states that "sanctions are policy tools used by governments to influence other governments and/or firms and citizens in other nations." Thus, economic sanctions are defined as "restrictions on commercial relations between citizens and firms of at least two countries."¹

Unfortunately, these simple and, at the same time, almost all-embracing explanations sometimes mislead researchers by concentrating their attention only on the relations between a sanctioning state/states (the sender) and the sanctioned country (the target). As a result, they limit the range of factors determining the success or failure of sanctions to such parameters as the decisiveness of the sender's political elite in implementing punitive measures completely, the potential of the economy of a sanctioned country to mitigate possible negative effects, the ability of the government of the targeted country to ensure the loyalty of its population, etc.² At the same time, the role of third countries, the international environment and international cooperation have often been underestimated, but in the age of globalization these aspects have acquired special importance. Thus, as stated by some researchers, nowadays economic sanctions could work effectively only in a situation with international consensus backing their implementation or, at least, with the support of major international players and the trading partners of a sanctioned country.³

The international environment is an especially important factor for American sanctions against Iran. Since 1979, economic cooperation between the United States and the Islamic Republic of Iran (IRI) has been minimal. As a result, the United States could exercise its influence on the Iranian economy only through interaction with the international community (by using punitive measures and incentives to limit its ability to cooperate with the IRI). Iran, in turn, can also mitigate the negative influence of U.S. sanctions, mainly by establishing an appropriate system of international relations. Under these circumstances, the following factors are vitally important for the emergence of opportunities to bypass American sanctions:

• The attitude of Iran's main trading partners towards U.S. sanctions

• The readiness of America's partners to uphold the U.S. sanctions and implement their own punitive measures against Iran in practice

• The existence of so-called "black knights" — a term that some researchers apply to countries that are less important trading partners of the targeted state but are able to use the punitive measures as a "lucrative opportunity" to increase their presence in the markets of the sanctioned country as the bigger players leave and, in doing so, mitigate the negative effect of the punitive measures.⁴