Edward J. Snowden, the former National Security Agency contractor, said in an extensive interview this month that he did not take any secret N.S.A. documents with him to Russia when he fled there in June, assuring that Russian intelligence officials could not get access to them. He also asserted that he was able to protect the documents from China's spies because he was familiar with that nation's intelligence abilities, saying that as an N.S.A. contractor he had targeted Chinese operations and had taught a course on Chinese cybercounterintelligence. There's a zero percent chance the Russians or Chinese have received any documents," he said. Mr. Snowden added that inside the spy agency "there's a lot of dissent." But he said that people were kept in line through "fear and a false image of patriotism," which he described as "obedience to authority." He said he believed that if he tried to question the N.S.A.'s surveillance operations as an insider, his efforts "would have been buried forever," and he would "have been discredited and ruined." Mr. Snowden said he finally decided to act when he discovered a copy of a classified 2009 inspector general's report on the N.S.A.'s warrantless wiretapping program during the Bush administration. After reading about the program, which skirted the existing surveillance laws, he concluded that it had been illegal, he said. "If the highest officials in government can break the law without fearing punishment or even any repercussions at all," he said, "secret powers become tremendously dangerous."