It happened at least once. Do you know Operation Chastise, the destruction of Ruhr water dams on 16/17 May 1942? This operation was the brainchild of Barnes Wallis, a British engineer. In March 1941, he had written a preliminary report, and had given a hundred copies to various people, including journalists. He even sent some copies to the still neutral United States where some German sympathiser could possibly read it.

His reasoning is that a widely distributed document would be considered by spies as an uninteresting document.

Source: The Dambusters Raid, John Sweetman, Arms and Armour, ISBN 1-85409-180-8 update corrected a few typos: "Rhur" -> "Ruhr", and "barrage" -> "dam" :-(