Conversation so far:
What did Brennan do as an advisor to Obama?
In late 2008, Brennan was reportedly the top choice to become the next Director of the CIA in the incoming Obama administration.
When did he begin in that position?
President Obama then appointed him to be his Deputy National Security Advisor for Homeland Security and Counterterrorism.

Question: What else did he do?
Self-contained rewrite: Besides being the Deputy National Security Advisor for Homeland Security and Counterterrorism advisor to President Obama, what else did John Brennan do?