Even more importantly, the status of the dollar as the worlds currency of reference and the dominance of US companies in international finance provide the US government with tremendous power over all participants in the formal non-cash financial system. It can make everybody conform to American law rather than to their local or international rules. German newspaper Frankfurter Allgemeine Zeitung has recently run a chilling story describing how that works (German). Employees of a German factoring firm doing completely legal business with Iran were put on a US terror list, which meant that they were shut off most of the financial system and even some logistics companies would not transport their furniture any more. A major German bank was forced to fire several employees upon US request, who had not done anything improper or unlawful.
Did not help at all.