Why was a Kitsap-based Navy submarine flying a pirate flag?

BREMERTON, Wash. -- An image posted to a Pentagon website featuring a picture of a Kitsap-based submarine flying the pirate flag is stirring some attention on the Internet.

A pic of the USS Jimmy Carter, a Seawolf-class nuclear-powered submarine, returning to Naval Base Kitsap-Bangor was posted to a military media site and tweeted Tuesday.

The seemingly innocuous picture was noticed by military journalist Ian Keddie. Keddie spotted a pirate flag in the picture, which may mean the sub was part of an operational action, he says.

The Washington Post reported on the picture, saying that some military historians say the flag means the sub participated in operations.

"The 450-foot-long vessel is one of three in its class and is specially modified to conduct some of America's most covert operations," the Post reported.

Keddie says flying the skull and crossbones flag - known as the Jolly Roger - is significant. The flag's presence on submarines goes back to World War I, the Post reported, when a British submarine sank a German battle cruiser. U.S. submarines in WWII occasionally flew the battle flag upon returning from patrols where destroyers were sunk.

U.S. submarine activity isn't openly discussed, the Post reported, and it is unclear why the flag was flown by the USS Jimmy Carter. Though it's unlikely the submarine torpedoed anything in combat, the flag could represent a more covert mission.

But many also took to Reddit to say don't read too much into the flag.

"Perhaps the sailors just wanted to have a little bit of harmless fun after a long deployment," Reddit user QuadiContract said. "Heaven forbid..."