WASHINGTON — That didn’t take long.

One day after the Dutton publishing company confirmed it planned to publish a new book on the killing of Osama bin Laden by an anonymous Navy SEAL who was on the mission, the writer has been outed.

The author of “No Easy Day, The First Hand Account of the Mission That Killed Osama Bin Laden” is Matt Bissonnette, a 36-year-old recently retired SEAL, according to Fox News, which cited “multiple sources.”

Dutton, a division of Penguin Group, was prepared to release the book under the pseudonym Mark Owen and was going to great lengths to hide the writer’s identity, planning to alter his voice and appearance during television interviews for the book’s Sept. 11 release.

The exposure could be trouble for Bissonnette since the bin Laden mission is still classified. Although the SEAL is retired, that doesn’t mean he is clear of legal liability, said Navy spokesman Lt. Cmdr. Chris Servello.

“Any service member who discloses classified or sensitive information could be subject to prosecution,” Servello told Fox.