The anthropologist Hugh Gusterson makes an important point in the Bulletin of the Atomic Scientists:
American leaders say they will avoid future Mannings and Snowdens by segmenting access to information so that individual analysts cannot avail themselves of so much, and by giving fewer security clearances, especially to employees of contractors such as Booz Allen Hamilton, where Snowden worked. This will not work. Segmentation of access runs counter to the whole point of the latest intelligence strategy, which is fusion of data from disparate sources. The more Balkanized the data, the less effective the intelligence. And, as Dana Priest and William Arkin make clear in their important book Top Secret America, intelligence agencies are collecting so much information that they have to hire vast numbers of new employees, many of whom cannot be adequately vetted. Since 9/11 the National Security Agency's workforce has grown by a third, to 33,000, and the number of private companies it relies on for contractors has tripled to close to 500. The more people know your secrets, the more likely it is they will leak out.