How will you prosecute them? Not only most scammers are nameless, but most are from countries where government needs to fix lot of things before they are effective against scammers.
You provide the incentives to the countries to fix their problem by cutting them completely off. If someone using a bank in Cyprus did it, you tell Cyprus government that in 48 hours the Fed will block all transactions with that bank and you block it. They move to another bank, you repeat it. Eventually Cyprus government ( and Cyprus banks ) have to make a choice - continue to tolerate scammers using their banks and be locked out totally out of the US financial system or crack down on the scammers.
Follow the money and report the issue to the institutions along the line. If they refuse to shut down the scammers and to stop facilitating their crimes, shut the institutions down for being an accessory.
Don't get me wrong; I'd love to see them picking up trash on the side of the highway for next twenty years of their life, or worse. But calling everything "terrorism" really reminds me of the years following 2001.