Many headlines and stories (including some of ours) have been saying that a "double agent" infiltrated al-Qaida in the Arabian Peninsula and foiled a plot to get another underwear bomb aboard a U.S.-bound passenger jet.

But we've been looking at definitions of spy terms and think that based on what we have been told so far, the person at the center of the story wasn't a double agent.

That character was at least an "agent."

But "mole" may be the best definition.

First, though, some background in case you need to catch up on the story.

As NPR's Dina Temple-Raston said today on Morning Edition, the story from authorities now is that "a foreign intelligence service sent an agent to infilitrate al-Qaida's arm in Yemen." He was basically told, Dina added, to "volunteer for a suicide mission."

That person reportedly gained the terrorist group's confidence and eventually was given the task of going on an airborne suicide mission, with the underwear bomb as the weapon. Instead, according to U.S. officials, this week the agent/mole turned the bomb over to that foreign intelligence service — which then passed it to the FBI for analysis.

Now, the definitions.

A "double agent," according to the International Spy Museum's Language of Espionage webpage, is "a spy who works for two intelligence services, usually against his or her original employer." Mark Stout, the museum's historian, tells us a double agent is usually "someone you've recruited in a foreign government."

If what we've been told is true, this person wasn't working against his or her original employer. So, cross out "double agent."

Stout agrees with that conclusion. "Double agent is technically not correct in this case," he says.

An "agent," according to the Spy Museum, is "a person unofficially employed by an intelligence service."

That sounds fine. Perhaps a little dull, but OK.

Then there's "mole." The Spy Museum says that is "an agent of one organization sent to penetrate a specific intelligence agency by gaining employment."

If the person in this case was sent by a foreign intelligence service to infiltrate al-Qaida's arm in Yemen and was indeed told to volunteer for a suicide mission, those would seem to fit the mole definition.

"Mole would be fine" in this case, says Stout. "It's a good term."

Of course, being a spy caper, it's not that simple.

One strike against calling our character a mole: Al-Qaida is not "a specific intelligence agency." Stout doesn't think that's a deal breaker, though. Intelligence agencies and foreign terrorist networks have the same goals, he says — to do harm to their enemies. They just use different methods to achieve those ends.

But there's this, from the master of spy novels, John Le Carre:

"A 'mole' is, I think, a genuine KGB term for somebody of the Philby sort who is recruited at a very tender age."

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