A defector from China has revealed some of the innermost secrets of the Chinese government and military, including details of its nuclear command and control system, according to American intelligence officials.

Businessman Ling Wancheng disappeared from public view in California last year shortly after his brother, Ling Jihua, a former high-ranking official in the Communist Party, was arrested in China on corruption charges.

Ling Wancheng, the defector, has been undergoing a debrief by FBI, CIA, and other intelligence officials since last fall at a secret location in the United States, said officials familiar with details of the defection who spoke on condition of anonymity. The defector is said to be a target of covert Chinese agents seeking to capture or kill him.

Among the information disclosed by Ling are details about the procedures used by Chinese leaders on the use of nuclear weapons, such as the steps taken in preparing nuclear forces for attack and release codes for nuclear arms.