Is the US dollar's survival as the favoured 'reserve' currency for international settlements due to its strength? Or to the relative frailty of other currencies? The only alternative contender today is the Chinese yuan. The yuan/dollar exchange rate is controlled by China through its immense holdings of US Treasury bills, the largest amount held by any foreign country. It is estimated that the yuan would appreciate by at least 30% against the dollar if the Chinese allowed it to float freely, and that would be the end of all those cheap Chinese imports.