Kevin Warsh, the incoming chair of the U.S. Federal Reserve, returns to the central bank with an ambitious reform agenda and the looming threat of intimidation by the U.S. President Donald Trump.

Never before has a chair of the US Federal Reserve been so controversial. Who is Kevin Warsh? Can he preserve the Fed's independence, or will he become Donald Trump's puppet?

Never before has a chair of the US Federal Reserve been so controversial. Who is Kevin Warsh? Can he preserve the Fed's independence, or will he become Donald Trump's puppet?