The head of BAE Systems PLC's (BA.LN) U.S. subsidiary has quit to become chief executive of U.S. defense contractor SAIC Inc. (SAI), according to a person familiar with the matter.

A spokeswoman for SAIC said only that the San Diego, Calif., company didn't plan to make any announcements Monday.

Walt Havenstein, 59 years old, will step down as president and chief executive of BAE Systems Inc. June 26 and will leave the company Sept. 20, BAE Systems said. He steps down as a director immediately. Havenstein has worked at BAE Systems for 10 years.

Gen. Anthony Zinni has been appointed chairman of BAE Systems Inc.'s board, where he currently serves as a director, and as acting president and CEO, pending the appointment of a permanent successor to Havenstein, BAE Systems said.

-By Jonathan Buck, Dow Jones Newswires; +44 (0)207 842 8237; jonathan.buck@dowjones.com