Since I didn't really talk through this before, a bit of an effort post.

OFAC sanctioned Suex, a crypto exchange based in the Czech Republic, less than a month ago[1]. As far as I can tell it is gone from the face of the earth. Here's why:

> As a result of today’s designation, all property and interests in property of the designated target that are subject to U.S. jurisdiction are blocked, and U.S. persons are generally prohibited from engaging in transactions with them. Additionally, any entities 50% or more owned by one or more designated persons are also blocked. In addition, financial institutions and other persons that engage in certain transactions or activities with the sanctioned entities and individuals may expose themselves to sanctions or be subject to an enforcement action.

    suex.io.  676 IN SOA ns-648.awsdns-17.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400

suex.io's hosting is gone due to OFAC's ruling: Amazon is barred from providing them service.

They used to take Visa & Mastercard[2] – even if they were online today, they wouldn't find a payment processor in the world willing to touch them: that would expose the payment processor to OFAC sanctions which is as close to "existential risk" as you can get in finance.

Suex was listed on the SDN list[3]. As a result no US based exchange can touch any crypto from those addresses. If, say, you wanted to cash out that crypto by sending it to Coinbase, they'd be legally required to freeze it and deny you access to it: otherwise, they're at risk of OFAC sanctions.

Every bank in the US monitors the OFAC SDN list, and as a result, they will be monitoring transactions. If Suex attempted to move their money into a bank account controlled by the US, they'd be blocked. But most likely their accounts are already frozen, because OFAC jurisdiction attaches when funds pass through any US financial institution or any foreign financial institution owned by a US person.

OFAC has recently decided that the mere presence of US dollars in a financial transaction is sufficient to establish jurisdiction: if Suex had their entirely foreign owned bank process any transactions in dollars, this would cause a US counterparty to indirectly provide financial services to an SDN. This risks sanctions at their foreign-owned bank.

At the end of the day, most global financial institutions assume a US nexus is present and deny any service to targets of US sanctions – the risk is much lower.

To wrap this up, OFAC has published an interesting guide[4] to sanctions that directly relate to cryptocurrency, and it's well worth a read.

[1]: https://home.treasury.gov/news/press-releases/jy0364

[2]: https://web.archive.org/web/20210414074952/https://suex.io/

[3]: https://home.treasury.gov/policy-issues/financial-sanctions/...

[4]: https://home.treasury.gov/system/files/126/virtual_currency_...