This article says that Iran is exporting arms to Sudan, Russia, Ethiopia, Bolivia, Venezuela, Western sahara, etc.
Given that Iran cannot use a US or European financial network, how does Iran earn money from these sales? In other words, how do they bring their export money home?
Iran spends considerable time and effort working to circumvent European and US-controlled financial networks and systems. It's methods are numerous and constantly shifting as those nations that sanction the country are similarly constantly working to adapt and improve their enforcement mechanisms.
That evolution takes many forms and it's trajectory gives us some insight into how Iran tries to keep the dollars flowing.
Enforcement actions involve a growing list of sanctioned individuals and business entities as Iran moves financial assets from shell company to shell company (essentially money laundering done at the state scale). Thus, a portion of Iran's strategy involves having deniable financial assets which it directs to those parties it wishes to pay. The risk to the seller is that the transactions are traced back to Iran and the funds end up frozen.
Networks of middlemen are sometimes willing to do this kind of business on Iran's behalf. The risks, as are evident from the source, are similar - in this case a 39-member network of such individuals based out of the UAE was targeted.
As noted by others, cash is all but impossible to sanction. Cash has several analogs, as well, including gold and cryptocurrency (North Korea's favored mechanism). Gold, in particular, is only one step removed from going full barter-economy which is also a means to escape financial networks as they can't stop the flow of goods - only the electronic transfer of funds.
From a 2018 FinCEN advisory:
Iran also has a history of using precious metals to evade sanctions and gain access to the financial system and may seek to use virtual currencies in the future.
later:
Senior officials of the CBI have played a critical role in enabling illicit networks, using their official capacity to procure hard currency and conduct transactions for the benefit of the IRGC-QF and its terrorist proxy group, Lebanese Hizballah.4 The CBI has also been complicit in these activities.
So that's gold and cash right there.
Financial sanctions are only as good as the willingness to cooperate by various network actors. If - as proposed by Russia, China, and Iran at various points - BRICS were to form their own financial network as an explicit competitor to US-controlled and European networks then the efficacy of sanctions would be greatly diminished.
