The U.S. dollar fell Thursday to its lowest point since the summer of 2008, but officials aren't showing signs that they are alarmed by the currency's descent or acting to stem it.

In recent days, the nation's top two economic policy makers—Federal Reserve Chairman Ben Bernanke and Treasury Secretary Tim Geithner—have publicly expressed their desire for a strong dollar. But there is little indication of a change in policy from either the Fed or Treasury—or in underlying economic conditions—that would alter the currency's downward...