A former Navy SEAL's insider account of the US raid that killed Osama bin Laden contains classified information, an official says.
Pentagon press secretary George Little told reporters That an official review of the book, No Easy Day, determined that it reveals what he called "sensitive and classified" information.
He was not more specific but said the book should have been submitted to the Pentagon before publication for a formal review of potential disclosures.
A lawyer for the author, Matt Bissonnette, has disputed that he was legally obliged to have the book screened before publication.
Mr Little would not say what damage may result from the book's revelations.
He said the Pentagon has not taken steps to stop the book from being sold on US military installations.