The Fed Vice Chairman Stanley Fischer said in a speech on Monday that the Fed was concerns about the developments in the global financial markets, which could have a negative impact on the U.S. economy.

"Increased concern about the global outlook, particularly the ongoing structural adjustments in China and the effects of the declines in the prices of oil and other commodities on commodity exporting nations, appeared early this year to have triggered volatility in global asset markets," he said.

"At this point, it is difficult to judge the likely implications of this volatility. If these developments lead to a persistent tightening of financial conditions, they could signal a slowing in the global economy that could affect growth and inflation in the United States," the Fed vice chairman added.

Fischer pointed out that he did know the Fed's next move.