epa03798064 (FILE) A file photograph showing US Chairman of the Joint Chiefs of Staff General Martin E. Dempsey testifies before the Senate Armed Services Committee hearing on Capitol Hill in Washington DC, USA, 07 February 2013. Media reports on 23 July 2013 state that General Dempsey has drawn up the US military options, costs, risks and benefits of possible US military involvement in the Syrian conflict, in an open letter to US Senators. EPA/MICHAEL REYNOLDS *** Local Caption *** 50699278