Today John O. Brennan will face his Senate confirmation hearing for the position of C.I.A. director. Brennan served as President Obama's chief counter-terrorism adviser in the President's first term, and he quickly learned the threats posed by Al Qaeda in the Arabian Peninsula. On Christmas Day 2009, on a plane traveling from Amsterdam to Detroit, passengers apprehended would-be bomber Umar Farouk Abdulmutallab. Al Qaeda in the Arabian Peninsula  later claimed responsibility, and Abdulmutallab admitted to training in Yemen. The bomb designer who worked with Abdulmutallab also made the package bombs sent from Yemen to Dubai and Great Britain in the fall of 2010. Both episodes seem to have left a deep impression on Brennan, who, in the wake of Osama bin Laden's death in May 2011, helped shift the C.I.A.'s focus from Pakistan and Afghanistan to Yemen and Northwest Africa. Brennan is also known as a chief architect of President Obama's drone program in the region.   If confirmed, how would Brennan shape the C.I.A.? Glenn Greenwald  is a columnist on civil liberties and U.S. national security issues for the Guardian. He explores Brennan's foreign policy influence in the region, and his potential role in Obama's second term.