The Iran programme is the oldest continuously operating major sanctions regime and, partly for that reason, the one with the deepest enforcement record. A large proportion of the correspondent banking cases on this site are Iran cases.
Layers
Iran-related restrictions have accumulated in layers rather than replacing one another: measures dating from 1979 and the 1990s, the proliferation-related designations of the 2000s, the UN measures, the extensive secondary sanctions architecture, the partial relief under the 2015 nuclear agreement, and its reimposition from 2018.
The result is that the applicable rule for a given transaction depends on which layer it falls under, and the answer is frequently not intuitive.
Its contribution to the technique record
Iran-related enforcement produced most of the published material on origin-based restrictions — the Sojitz case turns on cargo origin with no Iranian party in the payment chain — on third- country distributors, as in Epsilon, and on the entire correspondent banking sequence from Credit Suisse in 2009 onward.
The shipping advisories issued in 2019 and 2020 also draw heavily on Iran-related conduct, and supply a large share of the maritime indicators used on this site.
How the money moves
Since 2025 US Treasury and FinCEN have published a run of releases about the payment side of the programme: Iran-based exchange houses, bank-appointed “rahbar” companies and the front companies they use in Hong Kong and the UAE. The mechanism has its own page on exchange-house and rahbar networks, and FinCEN’s count of what its data shows is in a data note.