Kahn, then a newspaper journalist, was contracted to write a book on cryptography in 1961. He began writing it part-time, at one point quitting his regular job to work on it full-time. The book was to include information on the National Security Agency (NSA), and according to author James Bamford writing in 1982, the agency attempted to stop its publication and considered publishing a negative review of Kahn's work in the press to discredit him. A committee of the United States Intelligence Board concluded that the book was "a possibly valuable support to foreign COMSEC security authorities" and recommended "further low-key actions as possible, but short of legal action, to discourage Mr. Kahn or his prospective publishers." Kahn's publisher, the Macmillan company, handed over the manuscript to the federal government for review without Kahn's permission on March 4, 1966. Kahn and Macmillan eventually agreed to remove some material from the manuscript, particularly concerning the relationship between the NSA and its British counterpart, the GCHQ, because Kahn felt pressured by the intelligence community.