At the heart of Mr. Snowden’s narrative was his claim that while he may have incidentally “touched” other data in his search of NSA files, he took only documents that exposed the malfeasance of the NSA and gave all of them to journalists. Yet even as Mr. Snowden’s narrative was taking hold in the public realm, a secret damage assessment done by the NSA and Pentagon told a very different story. According to a unanimous report declassified on Dec. 22 by the House Permanent Select Committee on Intelligence, the investigation showed that Mr. Snowden had “removed” (not merely touched) 1.5 million documents. That huge number was based on, among other evidence, electronic logs that recorded the selection, copying and moving of documents. The number of purloined documents is more than what NSA officials were willing to say in 2013 about the removal of data, possibly because the House committee had the benefit of the Pentagon’s more-extensive investigation. But even just taking into account the material that Mr. Snowden handed over to journalists, the December House report concluded that he compromised “secrets that protect American troops overseas and secrets that provide vital defenses against terrorists and nation-states.” These were, the report said, “merely the tip of the iceberg.” The Pentagon’s investigation during 2013 and 2014 employed hundreds of military- intelligence officers, working around the clock, to review all 1.5 million documents. Most had nothing to do with domestic surveillance or whistle blowing. They were mainly military secrets, as Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, testified before the House Armed Services Committee on March 6, 2014. It was not the quantity of Mr. Snowden’s theft but the quality that was most telling. Mr. Snowden’s theft put documents at risk that could reveal the NSA’s Level 3 tool kit—a reference to documents containing the NSA’s most-important sources and methods. Since the agency was created in 1952, Rus