The most obvious pick would be Mike Vickers, now undersecretary of defense for intelligence and, before that, assistant secretary for Special Operations/Low Intensity Conflict.
A former special-forces officer and CIA operative, Vickers is best known for his role arming the Afghan resistance fighters against the Soviet army in 1980s Afghanistan. He had also been on the list of those considered to be CIA director.
There are other possibilities. For example, there’s Matt Olsen, who’s now head of the National Counterterrorism Center (NCTC) — though he’s only been in that job since August 2011.
Olsen ran the Guantanamo task force in 2009, charged with figuring out what to do with each detainee there, figure out where they might go, and has also been general counsel for National Security Agency..
Another name being heard is Leslie Ireland, a career intelligence officer and former national intelligence officer for Iran.. She’s now assistant secretary of Treasury for intelligence and analysis. She is said to have impressed Obama in pre-inauguration days when she was tasked with giving him his daily intel briefing.