What is Triffin Paradox?

What is Triffin Paradox?
The Triffin dilemma, less commonly called Triffin paradox, is the fundamental problem of the United States dollar's role as reserve currency in the Bretton Woods system, or more generally of a national currency as reserve currency.

By the early 1960s, an ounce of gold could be exchanged for $40 in London, even though the price in the U.S. was $35. This difference showed that investors knew the dollar was overvalued and that time was running out.
There was a solution to the Triffin dilemma for the U.S.: reduce the number of dollars in circulation by cutting the deficit and raising interest rates to attract dollars back into the country.

Triffin Paradox pointed out the basic contradiction in the Bretton Woods system especially when dollar started losing its credibility to convert into gold at the promised rate of $35 per ounce of gold. The contradiction was that only when US ran deficits, could other countries build up forex reserves; but as soon as the US BoP deficits became unsustainably large, other countries lost faith, leading to demise of Bretton Woods in 1971.