Flournoy withdraws from consideration as US defence secretary Ms Flournoy, who has retained close ties to the Obama administration, first came to prominence analysing the failure of the 1993 "Black Hawk Down" mission in which 18 US troops were killed in street fighting in Somalia. She was placed at the head of list of likely successors by the New York Times, and was seen as a favourite of Hillary Clinton who could potentially have remained in post if Mrs Clinton won the White House in 2016. A rapidly narrowing field is now headed by Robert Work, a Marine of 27 years who is Mr Hagel's deputy, and Jeh Johnson, the current secretary of homeland security.