In part, Crowley said:
The unauthorized disclosure of classified information is a serious crime under U.S. law. My recent comments regarding the conditions of the pre-trial detention of Private First Class Bradley Manning were intended to highlight the broader, even strategic impact of discrete actions undertaken by national security agencies every day and their impact on our global standing and leadership. The exercise of power in today's challenging times and relentless media environment must be prudent and consistent with our laws and values.
Given the impact of my remarks, for which I take full responsibility, I have submitted my resignation as Assistant Secretary for Public Affairs and Spokesman for the Department of State.
Crowley authored an article for the official journal of ACS, The Harvard Law & Policy Review (HLPR), dedicated to "ideas and recommendations" for a new administration. The article, "Homeland Security and the Upcoming Transition: What the Next Administration Should Do to Make Us Safe at Home," is available here.
Think Progress has more on Crowley here.