The monetary system broke down in 1971 while the United States was still a dominant power.

Test: whether the international monetary system broke down in 1971 (the end of Bretton Woods gold convertibility, when Nixon closed the gold window on 15 August 1971) while the US was still the dominant world power. True: the 1971 suspension of dollar–gold convertibility is confirmed, and the US was then the leading economic and military power. Mostly true: the breakdown is dated slightly differently, for example as a process running from 1971 to 1973. Mostly false: the events of 1971 were a minor adjustment rather than a breakdown, or the US was not dominant at the time. False: no such breakdown occurred around 1971.

Set before the research began.

1. E1 In Pursuit of Primacy Oxford Academic (Oxford University Press) · 18 December 2014

   “Facing internal and external constraints, including fiscal crises and resurgent isolationism, the Nixon administration worked in its first term t”

2. E2 In Pursuit of Primacy OUP Academic (Oxford University Press) · 18 December 2014

   “Abstract. Facing internal and external constraints, including fiscal crises and resurgent isolationism, the Nixon administration worked in its first term t”

3. E3 Nixon Ends Convertibility of U.S. Dollars to Gold and Announces Wage/Price Controls Federal Reserve History · 4 August 2011

   “Foreign governments could no longer exchange their dollars for gold; in effect, the international monetary system turned into a fiat one. A few months later the Smithsonian agreement attempted to maintain pegged exchange rates, but the Bretton Woods system ended soon thereafter.”

4. E4 The Smithsonian Agreement Federal Reserve History · 7 April 2025

   “Within fifteen months, the Bretton Woods system collapsed.”

5. E5 The Smithsonian Agreement Federal Reserve History · 7 April 2025

   “Within a month nearly all major currencies were floating against the dollar. The Bretton Woods system was finished”

6. E6 Nixon Ends Convertibility of U.S. Dollars to Gold and Announces Wage/Price Controls Federal Reserve History · 4 August 2011

   “The U.S. share of world output decreased and so did the need for dollars, making converting those dollars to gold more desirable.”

E3 (Federal Reserve History, "Nixon Ends Convertibility of U.S. Dollars to Gold") confirms the event the criteria name: foreign governments could no longer exchange dollars for gold, and the international monetary system became a fiat one. E3, E4 and E5 show that the Bretton Woods system ended afterwards, within fifteen months according to E4, with nearly all major currencies floating against the dollar (E5). That makes the breakdown a process rather than a single event, which the criteria place under mostly true. On US dominance, E6 notes a falling US share of world output, and E1/E2 describe the Nixon administration pursuing primacy. Neither says the US was not the leading power, but the quoted evidence gives no explicit date and does not directly confirm US dominance.