Conversation so far:
When did John O.
Brennan's time as a counterterrorism advisor to Obama begin?
President Obama then appointed him to be his Deputy National Security Advisor for Homeland Security and Counterterrorism, the President's.
What led to his appointment?
In August 2009, Brennan criticized some Bush-administration anti-terror policies.
Did he have a hand in any historically significant counterterrorism?
Brennan was present in the Situation Room in May 2011 when the United States conducted the military operation.
What military operation was that?
that killed Osama bin Laden.
Did he receive any recognition or awards?
said that using the second term, which means one who is struggling for a holy goal, gives "these murderers.

Question: When did he cease to be in that role?
Self-contained rewrite: When did Brennan cease to be Obama's Deputy National Security Advisor for Homeland Security and Counterterrorism?