John W. Magaw resigned today as Under Secretary of Transportation for Security, the Department of Transportation announced.

James M. Loy will replace Magaw, who has headed the Transportation Security Administration (TSA) since January. Upon his retirement as Commandant of the U.S. Coast Guard, Loy was recently named Deputy Under Secretary and Chief Operating Officer of the TSA.

A senior administration official told The Associated Press Magaw apparently left TSA for personal reasons.

“John Magaw is a dedicated public servant with a lifetime of achievements in the law enforcement field, and we all owe him a debt for his role in the start-up phase of TSA,” Secretary of Transportation Norman Y. Mineta said.