What/Are there any boundaries to sanctions?

Question

From: https://www.nbcnews.com/politics/justice-department/iranian-national-charged-115-million-sanctions-busting-scheme-n1128071

When Karimi was interviewed by FBI agents and others earlier this month, the indictment says, he falsely stated that he believed that international sanctions against Iran did not apply to Iranian companies or persons.

The article also mentions the project was in Venezuela which I guess is also subject to sanctions.

My questions is if countries that are subject to sanctions e.g. Iran, Venezuela, North Korea etc. doing business with each other is that also against the sanctions or the sanctions must involve both non-sanctioned and sanctioned countries?

Answer 1

Sanctions passed by the US only apply to US residents, or companies doing business in or with the US. So if a North Korean buys Iranian oil, that North Korean can no longer deal with the US. And people who deal with this North Korean can no longer deal with the US, either. And people who deal with people who deal with this North Korean can no longer deal with the US. And so on.

So companies have a choice. Do business with companies connected to the United States, or do business with companies connected to Iran. They cannot do both.

Sanctions passed by the UN Security Council are a different matter.