> Despite claiming they only send messages, in effect money is moved and there are documented cases of it being seized off the wire by the US even in EU<->EU state transactions.
The ability of the US to seize USD transaction has nothing to do with any control they might have over SWIFT. All USD transfers -- even USD transfers between two EU citizens -- hapen via a US bank, because only US banks can have a USD balance.
There are USD balances right across the world. Some of them are backed with cash (really!). That's fundamentally because, unlike bitcoin or company shares, currency is what's known as a 'non-consolidated' asset: ie. there is no central ledger anywhere in the world with a complete list of who owns every piece of currency on issue, like exists for Bitcoin on the blockchain.
The ability of the US to seize USD transaction has nothing to do with any control they might have over SWIFT. All USD transfers -- even USD transfers between two EU citizens -- hapen via a US bank, because only US banks can have a USD balance.
The actual transfers happen by way of so-called US "intermediate" banks, who perform the actual USD transfer. The process is described here: https://bitcoinfoundation.org/2012/12/international-bank-tra...