Flag of the United States Assistant Secretary of the Navy.  It dates from 1892, using the flag of the Secretary of the Navy with reversed colors. At the time, this was just one person, but nowadays there are four Assistant Secretaries. It is defined in naval regulations, document NTP 13(B) [1] section 1808, as:

The flags of each of the Assistant Secretaries of the Navy are the same design as  that for the Secretary of the Navy except that the field is white and the anchor and stars are blue. Gold fringe is authorized for use with the flag when it is displayed in a static, indoor position. The cord and tassels are of golden yellow. The flag is the personal flag of the Assistant Secretaries of the Navy for Financial Management, Installation and Logistics, and Research and Development.
For more information, see SeaFlags.
Modified from File:US-SecretaryOfTheNavy-Flag.svg
Carl Lindberg