The Specially Designated Nationals, or SDN, list is a compilation of individuals and entities owned, controlled by, acting for or on behalf of designated countries, according to the U.S. Department of Treasury. Assets of those on the list are blocked, and U.S. citizens are prohibited from doing business with them.
Individuals, groups and entities on the SDN list are composed of governments, individuals and corporations that are considered unsafe to deal with, such as terrorists and narcotics traffickers, notes the Cornell University Law School Legal Information Institute. The list is managed by the Bureau of Industry and Security, a branch of the Department of Commerce. It regulates the export of commodities and technology that could compromise national security, should it fall into the wrong hands.