From the Overview and Objectives: "This report analyzes U.S. and international sanctions against Iran. CRS [Congressional Research Service] has no way to independently corroborate whether any individual or other entity might be in violation of U.S. or international sanctions against Iran. The report tracks implementation of the various U.S. laws and executive orders. Some sanctions require the blocking of U.S.-based property of sanctioned entities, but no information has been released from the executive branch indicating the extent, if any, to which any such property has been blocked."
CRS Report for Congress, RS20871
Congressional Research Service: https://crsreports.congress.gov/