If it was shot by a government photographer you can ‘shop it all you want.*
http://www.usa.gov/copyright.shtml
“A United States government work is prepared by an officer or employee of the United States government as part of that person’s official duties.
It is not subject to copyright in the United States and there are no copyright restrictions on reproduction, derivative works, distribution, performance, or display of the work. Anyone may, without restriction under U.S. copyright laws:
reproduce the work in print or digital form;
create derivative works;
perform the work publicly;
display the work;
distribute copies or digitally transfer the work to the public by sale or other transfer of ownership, or by rental, lease, or lending.”
*My disclaimer: I am not an attorney, nor am I the son of an attorney, nor would I represent myself as an attorney in any way; therefore I feel completely free to dispense legal advice with impunity. Your mileage may vary.