The Bush administration, seeking to limit leaks of classified information, has launched initiatives targeting journalists and their possible government sources. The efforts include several FBI probes, a polygraph investigation inside the CIA and a warning from the Justice Department that reporters could be prosecuted under espionage laws. In recent weeks, dozens of employees at the CIA, the National Security Agency and other intelligence agencies have been interviewed by agents from the FBI's Washington field office, who are investigating possible leaks that led to reports about secret CIA prisons and the NSA's warrantless domestic surveillance program, according to law enforcement and...