WASHINGTON - The head of the CIA's Counterterrorism Center, who presided over the agency's drone campaign and directed the hunt for Osama bin Laden, is being removed from his post, officials said, a watershed moment as the CIA turns its focus to a new generation of extremist threats.

The move, part of a major reorganization under CIA Director John Brennan, ends a nine-year tenure during which the center was transformed into a paramilitary force that employed armed drones to kill thousands of suspected terrorists and militants but also killed an unknown number of civilians.

As the architect of that campaign, the CTC chief came to be regarded as an Ahab-like figure known for dark suits and a darker demeanor. He could be merciless toward subordinates but was also revered for his knowledge of terrorist networks and his ability to run an organization that became almost an agency unto itself. He embodied a killing-centric approach to counterterrorism that enraged many Muslims, even though he is a convert to Islam.

Because he remains undercover, the Washington Post has agreed to withhold his full name. He has been publicly identified in the past by both his actual first name, Mike, as well as that of his CIA-created identity, Roger.

U.S. officials said that Roger is expected to remain at the CIA in a new assignment that has yet to be determined and that he is being replaced by an agency veteran who has held a series of high-level positions, including running the CIA's operations in Afghanistan. His name is Chris.

Current and former U.S. officials said that the switch does not appear to signal a change in direction for the CTC or a retreat from the CIA's willingness to use lethal force. "The new individual is just as aggressive with counterterrorism operations as the guy leaving," said a former senior U.S. intelligence official who worked closely with both officers.

A CIA spokesman described the outgoing CTC director as "one of the true heroes of the agency."