The online leak of data pilfered from the National Security Agency more likely came from an agency insider than from hackers linked to Russia, according to an expert on the intelligence community.

“If Russia had stolen the hacking tools, it would be senseless to publicize the theft, let alone put them up for sale,” James Bamford, a former naval intelligence officer, wrote in a column late Sunday evening. “It would be like a safecracker stealing the combination to a bank vault and putting it on Facebook.”