WASHINGTON — The Obama administration is clamping down on a technique that government officials have long used to join in public discussions of well-known but technically still-secret information: citing news reports based on unauthorized disclosures. A new pre-publication review policy for the Office of Director of National Intelligence says the agency’s current and former employees and contractors may not cite news reports based on leaks in their speeches, opinion articles, books, term papers or other unofficial writings. Such officials “must not use sourcing that comes from known leaks, or unauthorized disclosures of sensitive information,” it says. “The use of such...