US President-elect Donald Trump has threatened retaliation against governments that challenge the US dollar, vowing "100 percent tariffs" on countries that undercut the US currency.The system has evolved since that time and several countries have stopped indexing their currencies to the dollar,

His threat was directed at countries in the so-called BRIC alliance, which consists of Brazil, Russia, India, China, South Africa, Egypt, Ethiopia, Iran and the United Arab Emirates.