When the Treasury is not overly concerned with the dollar, market forces can prevail to raise or lower the exchange rate compared with euros, Swiss francs, yen or any other currency.

Sometimes, other central banks intervene to raise or lower their currencies relative to the dollar and the U.S. does not seem to care. China is notorious for this. Japan and Switzerland are other practiced currency manipulators.

The last fully coordinated currency market intervention was conducted by the G-7 in March 2011 at the time of the Fukushima, Japan, earthquake and tsunami that caused the collapse of a nuclear power plant and ultimately a crash of the Tokyo stock exchange.

The Japanese economy was weakened by the natural disaster. A weaker yen would have helped the economy with cheaper exports and more inflation. But insurance companies had to sell dollar-denominated assets and buy yen in order to pay yen-denominated claims for the disaster losses. The result was a stronger yen.