NEW YORK, July 9 (Reuters) - Federal Reserve Bank of New York President John Williams said Thursday there’s a valid debate going on about the ways the central bank can further shrink the size of its balance sheet and many of them rest on ways to change how the banking system uses reserves.

But whatever happens, any change “should be based on…making sure that we have a safe and sound banking system," Williams said at a conference at his bank. “I don't think the driver of this should be” focused on the amount of Fed balance sheet reduction that can be achieved and “it really should be, how do we improve and make and strengthen our financial system?”