After the Sept. 11 attacks, Bush gave the CIA, and later the military, authority to kill U.S. citizens abroad if strong evidence existed that an American was involved in organizing or carrying out terrorist actions against the United States or U.S. interests, military and intelligence officials said. The evidence has to meet a certain, defined threshold. The person, for instance, has to pose "a continuing and imminent threat to U.S. persons and interests," said one former intelligence official