A former Navy SEAL who penned a book on the clandestine raid that killed Osama bin Laden revealed classified information in his first-hand account and could face criminal charges, US officials have said. The Pentagon\'s warning came on Tuesday as the head of US Naval Special Warfare Command, Rear Admiral Sean Pybus, voiced outrage that some current or retired commandos were trying to cash in on their fame. \"I am disappointed, embarrassed and concerned,\" Pybus wrote in a letter to troops, denouncing some former SEALs for delving into partisan politics or \"hawking details about a mission against Enemy Number 1.\" The US Defense Department has already threatened legal action over \"No Easy Day,\" which was released on Tuesday, but officials previously had stopped short of saying whether the book had revealed state secrets. \"We believe that sensitive and classified information is contained in the book,\" Pentagon spokesman George Little told reporters. Asked if the US government would take legal action against the author, Little said officials were reviewing all options. \"Legal avenues are available to us. I\'m simply not going to get into what we may or may not decide,\" he said. But he repeated the Pentagon\'s view that the author violated non-disclosure agreements that required him to submit his first person account -- the first such eyewitness account of the bin Laden raid -- for review by the military before publication. Sending in the book for review was a simple matter of \"common sense\" and \"a no-brainer\" for anyone working in matters of national security, Little said. \"It is the height of irresponsibility not to have this kind of material checked for the possible disclosure of classified information. \"And we have very serious concerns after having reviewed the book.\" The former Navy commando wrote \"No Easy Day\" under a pseudonym, Mark Owen, but soon was identified in media reports as Matt Bissonnette. In the book, published by Penguin\'s Dutton imprint, he describes his role in the famed May 2011 raid on bin Laden\'s Pakistani hideout as well as in other operations in Iraq and Afghanistan during his 14-year career as a Navy SEAL. Last week, Bissonnette\'s lawyer offered a rebuttal to the Pentagon, insisting the author had not broken faith with his commitments and that the non-disclosure agreements did not apply to the bin Laden operation. In an author\'s note at the beginning of \"No Easy Day,\" Bissonnette said he went to great lengths to avoid uncovering sensitive details about tactics or technology, saying he had consulted a former special operations forces lawyer to review the manuscript. \"If you are looking for secrets, this is not your book,\" he wrote. But the book has angered many inside the military, including Pybus, who wrote to his troops that those trying to exploit their status as SEALS were damaging the elite unit\'s reputation and possibly putting lives in danger. \"We must immediately reconsider how we properly influence our people in and out of uniform NOT to seek inappropriate monetary, political, or celebrity profit from their service with NSW (naval special warfare),\" he wrote. The Pentagon said it did not plan to try to block sales of the book at shops on military bases, and unlike in some previous cases, there was no sign the government would move to buy up copies and have them pulped. If a court finds Bissonnette failed to uphold his confidentiality agreement, he could be forced to forfeit any profits from the book -- but if it rules he revealed classified information, the former trooper could face a potential prison sentence and other punishment. After a wave of publicity, \"No Easy Day\" jumped to the top of Amazon.com\'s list of best selling books, helped by customers\' pre-orders. The book, which was co-written with journalist Kevin Maurer, is outpacing the erotica hit \"Fifty Shades of Grey.\" In an excerpt from a television interview released Tuesday, Bissonnette insisted that the SEALs did not have orders to assassinate bin Laden. \"This was absolutely not a kill-only mission,\" the author told CBS News\' \"60 Minutes\" program. \"It was made very clear to us -- throughout our training for this that, \'Hey, if given the opportunity, this is -- this is not an assassination. \"\'You will capture him alive -- if feasible.\'\"