U.S. Federal Reserve Chairman Jerome Powell said Wednesday the first interest rate cut since the financial crisis was to "insure against downside risks" but didn't signal the start of a lengthy easing cycle, drawing a sharp rebuke from President Donald Trump.

"We're thinking of it as essentially in the nature of a mid-cycle adjustment to policy," Powell said at a news conference following the quarter percentage-point reduction. "It's not the beginning of a long series of rate cuts," he said, adding, "I didn't say it's just one" move.

Financial markets were whipsawed during the news conference as Powell struggled to define the rate path ahead. He attempted to explain how the cuts were mainly defensive, aimed at supporting the economy during a period of too low inflation, weakening global growth and trade tensions.