Disregard for internationally imposed economic sanctions

Circumvention of international sanctions
Smuggling through sanctions barriers
Violation of international export controls
Breach of blockade
Unilateral and multilateral economic sanctions imposed since the end of World War I have had some limited successes but have proved virtually useless when wielded by one strong power against another. The successes were achieved mostly against small countries when only modest foreign policy goals were sought.
The rules concerning breach of blockade and carriage of contraband are often mentioned as important examples of rules rendering the individual a subject of international law. These rules authorize belligerent states to seize and confiscate property belonging to nationals of other states. Thus international law prohibits breach of blockade and carriage of contraband. These rules make the individual a subject of duties but not a subject of responsibility under international law and, consequently not a subject of international law.
An example of sanctions with general lack of success were the USA efforts to halt the sale of grain and gas pipeline equipment to the former Soviet Union. In 1990, the German government was given a list of 50 German companies believed to be violating the United Nations embargo against Iraq. In 1993 it was alleged that corporations based in the USA were using lax law enforcement concerning sanctions to conduct business openly in Cuba and Libya through foreign subsidiaries.
Even when they do not do their intended job, sanctions can serve important political purposes, such as unifying world opinion concerning violations of internationally accepted behaviour; for example, the League of Nations' action when Italy invaded Ethiopia.
(F) Fuzzy exceptional problems