The problem was that the supply of such liabilities by the United States at a fixed exchange rate was elastic to the growing demand, but the American commitment to supply gold upon request at an equally fixed price was not.1 Already by the early 1960s, US monetary liabilities towards non-residents exceeded US gold holdings.
Hence the dilemma, which in Triffin’s day took the well-known, specific shape: if the United States refused to provide other countries with US dollars, trade would stagnate and the world economy would eventually be trapped in a deflationary bias; but if the United States provided an unlimited supply of dollars, the confidence that it would convert them into gold would erode confidence in its international currency.2  1  See, for example, Eichengreen 2011.